dgrove@google.com
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git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@7 260f80e4-7a28-3924-810f-c04153c831b5
2900 lines
114 KiB
HTML
2900 lines
114 KiB
HTML
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<script type="application/dart" src="dom-modify.dart"></script>
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<body>
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<div class="head">
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<p><a href="http://www.w3.org/"><img height=48 alt=W3C src="http://www.w3.org/Icons/w3c_home" width=72></a>
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<h1 id="title">Selectors</h1>
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<h2>W3C Working Draft 15 December 2005</h2>
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<dl>
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<dt>This version:
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<dd><a href="http://www.w3.org/TR/2005/WD-css3-selectors-20051215">
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http://www.w3.org/TR/2005/WD-css3-selectors-20051215</a>
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<dt>Latest version:
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<dd><a href="http://www.w3.org/TR/css3-selectors">
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http://www.w3.org/TR/css3-selectors</a>
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<dt>Previous version:
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<dd><a href="http://www.w3.org/TR/2001/CR-css3-selectors-20011113">
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http://www.w3.org/TR/2001/CR-css3-selectors-20011113</a>
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<dt><a name=editors-list></a>Editors:
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<dd class="vcard"><span class="fn">Daniel Glazman</span> (Invited Expert)</dd>
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<dd class="vcard"><a lang="tr" class="url fn" href="http://www.tantek.com/">Tantek Çelik</a> (Invited Expert)
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<dd class="vcard"><a href="mailto:ian@hixie.ch" class="url fn">Ian Hickson</a> (<span
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class="company"><a href="http://www.google.com/">Google</a></span>)
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<dd class="vcard"><span class="fn">Peter Linss</span> (former editor, <span class="company"><a
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href="http://www.netscape.com/">Netscape/AOL</a></span>)
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<dd class="vcard"><span class="fn">John Williams</span> (former editor, <span class="company"><a
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href="http://www.quark.com/">Quark, Inc.</a></span>)
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</dl>
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<p class="copyright"><a
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href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">
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Copyright</a> © 2005 <a href="http://www.w3.org/"><abbr
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title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup>
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(<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts
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Institute of Technology">MIT</abbr></a>, <a
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href="http://www.ercim.org/"><acronym title="European Research
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Consortium for Informatics and Mathematics">ERCIM</acronym></a>, <a
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href="http://www.keio.ac.jp/">Keio</a>), All Rights Reserved. W3C
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<a
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href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>,
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<a
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href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a>,
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<a
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href="http://www.w3.org/Consortium/Legal/copyright-documents">document
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use</a> rules apply.
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<hr title="Separator for header">
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</div>
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<h2><a name=abstract></a>Abstract</h2>
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<p><em>Selectors</em> are patterns that match against elements in a
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tree. Selectors have been optimized for use with HTML and XML, and
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are designed to be usable in performance-critical code.</p>
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<p><acronym title="Cascading Style Sheets">CSS</acronym> (Cascading
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Style Sheets) is a language for describing the rendering of <acronym
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title="Hypertext Markup Language">HTML</acronym> and <acronym
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title="Extensible Markup Language">XML</acronym> documents on
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screen, on paper, in speech, etc. CSS uses Selectors for binding
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style properties to elements in the document. This document
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describes extensions to the selectors defined in CSS level 2. These
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extended selectors will be used by CSS level 3.
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<p>Selectors define the following function:</p>
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<pre>expression ∗ element → boolean</pre>
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<p>That is, given an element and a selector, this specification
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defines whether that element matches the selector.</p>
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<p>These expressions can also be used, for instance, to select a set
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of elements, or a single element from a set of elements, by
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evaluating the expression across all the elements in a
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subtree. <acronym title="Simple Tree Transformation
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Sheets">STTS</acronym> (Simple Tree Transformation Sheets), a
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language for transforming XML trees, uses this mechanism. <a href="#refsSTTS">[STTS]</a></p>
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<h2><a name=status></a>Status of this document</h2>
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<p><em>This section describes the status of this document at the
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time of its publication. Other documents may supersede this
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document. A list of current W3C publications and the latest revision
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of this technical report can be found in the <a
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href="http://www.w3.org/TR/">W3C technical reports index at
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http://www.w3.org/TR/.</a></em></p>
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<p>This document describes the selectors that already exist in <a
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href="#refsCSS1"><abbr title="CSS level 1">CSS1</abbr></a> and <a
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href="#refsCSS21"><abbr title="CSS level 2">CSS2</abbr></a>, and
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also proposes new selectors for <abbr title="CSS level
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3">CSS3</abbr> and other languages that may need them.</p>
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<p>The CSS Working Group doesn't expect that all implementations of
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CSS3 will have to implement all selectors. Instead, there will
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probably be a small number of variants of CSS3, called profiles. For
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example, it may be that only a profile for interactive user agents
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will include all of the selectors.</p>
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<p>This specification is a last call working draft for the the <a
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href="http://www.w3.org/Style/CSS/members">CSS Working Group</a>
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(<a href="/Style/">Style Activity</a>). This
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document is a revision of the <a
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href="http://www.w3.org/TR/2001/CR-css3-selectors-20011113/">Candidate
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Recommendation dated 2001 November 13</a>, and has incorporated
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implementation feedback received in the past few years. It is
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expected that this last call will proceed straight to Proposed
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Recommendation stage since it is believed that interoperability will
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be demonstrable.</p>
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<p>All persons are encouraged to review and implement this
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specification and return comments to the (<a
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href="http://lists.w3.org/Archives/Public/www-style/">archived</a>)
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public mailing list <a
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href="http://www.w3.org/Mail/Lists.html#www-style">www-style</a>
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(see <a href="http://www.w3.org/Mail/Request">instructions</a>). W3C
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Members can also send comments directly to the CSS Working
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Group.
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The deadline for comments is 14 January 2006.</p>
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<p>This is still a draft document and may be updated, replaced, or
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obsoleted by other documents at any time. It is inappropriate to
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cite a W3C Working Draft as other than "work in progress".
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<p>This document may be available in <a
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href="http://www.w3.org/Style/css3-selectors-updates/translations">translation</a>.
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The English version of this specification is the only normative
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version.
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<div class="subtoc">
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<h2 id="test1"><a name=contents>Table of contents</a></h2>
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<ul class="toc">
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<li class="tocline2"><a href="#context">1. Introduction</a>
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<ul>
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<li><a href="#dependencies">1.1. Dependencies</a> </li>
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<li><a href="#terminology">1.2. Terminology</a> </li>
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<li><a href="#changesFromCSS2">1.3. Changes from CSS2</a> </li>
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</ul>
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<li class="tocline2"><a href="#selectors">2. Selectors</a>
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<li class="tocline2"><a href="#casesens">3. Case sensitivity</a>
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<li class="tocline2"><a href="#selector-syntax">4. Selector syntax</a>
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<li class="tocline2"><a href="#grouping">5. Groups of selectors</a>
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<li class="tocline2"><a href="#simple-selectors">6. Simple selectors</a>
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<ul class="toc">
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<li class="tocline3"><a href="#type-selectors">6.1. Type selectors</a>
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<ul class="toc">
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<li class="tocline4"><a href="#typenmsp">6.1.1. Type selectors and namespaces</a></li>
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</ul>
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<li class="tocline3"><a href="#universal-selector">6.2. Universal selector</a>
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<ul>
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<li><a href="#univnmsp">6.2.1. Universal selector and namespaces</a></li>
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</ul>
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<li class="tocline3"><a href="#attribute-selectors">6.3. Attribute selectors</a>
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<ul class="toc">
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<li class="tocline4"><a href="#attribute-representation">6.3.1. Representation of attributes and attributes values</a>
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<li><a href="#attribute-substrings">6.3.2. Substring matching attribute selectors</a>
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<li class="tocline4"><a href="#attrnmsp">6.3.3. Attribute selectors and namespaces</a>
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<li class="tocline4"><a href="#def-values">6.3.4. Default attribute values in DTDs</a></li>
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</ul>
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<li class="tocline3"><a href="#class-html">6.4. Class selectors</a>
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<li class="tocline3"><a href="#id-selectors">6.5. ID selectors</a>
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<li class="tocline3"><a href="#pseudo-classes">6.6. Pseudo-classes</a>
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<ul class="toc">
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<li class="tocline4"><a href="#dynamic-pseudos">6.6.1. Dynamic pseudo-classes</a>
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<li class="tocline4"><a href="#target-pseudo">6.6.2. The :target pseudo-class</a>
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<li class="tocline4"><a href="#lang-pseudo">6.6.3. The :lang() pseudo-class</a>
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<li class="tocline4"><a href="#UIstates">6.6.4. UI element states pseudo-classes</a>
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<li class="tocline4"><a href="#structural-pseudos">6.6.5. Structural pseudo-classes</a>
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<ul>
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<li><a href="#root-pseudo">:root pseudo-class</a>
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<li><a href="#nth-child-pseudo">:nth-child() pseudo-class</a>
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<li><a href="#nth-last-child-pseudo">:nth-last-child()</a>
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<li><a href="#nth-of-type-pseudo">:nth-of-type() pseudo-class</a>
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<li><a href="#nth-last-of-type-pseudo">:nth-last-of-type()</a>
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<li><a href="#first-child-pseudo">:first-child pseudo-class</a>
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<li><a href="#last-child-pseudo">:last-child pseudo-class</a>
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<li><a href="#first-of-type-pseudo">:first-of-type pseudo-class</a>
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<li><a href="#last-of-type-pseudo">:last-of-type pseudo-class</a>
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<li><a href="#only-child-pseudo">:only-child pseudo-class</a>
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<li><a href="#only-of-type-pseudo">:only-of-type pseudo-class</a>
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<li><a href="#empty-pseudo">:empty pseudo-class</a></li>
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</ul>
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<li class="tocline4"><a href="#negation">6.6.7. The negation pseudo-class</a></li>
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</ul>
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</li>
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</ul>
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<li><a href="#pseudo-elements">7. Pseudo-elements</a>
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<ul>
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<li><a href="#first-line">7.1. The ::first-line pseudo-element</a>
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<li><a href="#first-letter">7.2. The ::first-letter pseudo-element</a>
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<li><a href="#UIfragments">7.3. The ::selection pseudo-element</a>
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<li><a href="#gen-content">7.4. The ::before and ::after pseudo-elements</a></li>
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</ul>
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<li class="tocline2"><a href="#combinators">8. Combinators</a>
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<ul class="toc">
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<li class="tocline3"><a href="#descendant-combinators">8.1. Descendant combinators</a>
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<li class="tocline3"><a href="#child-combinators">8.2. Child combinators</a>
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<li class="tocline3"><a href="#sibling-combinators">8.3. Sibling combinators</a>
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<ul class="toc">
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<li class="tocline4"><a href="#adjacent-sibling-combinators">8.3.1. Adjacent sibling combinator</a>
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<li class="tocline4"><a href="#general-sibling-combinators">8.3.2. General sibling combinator</a></li>
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</ul>
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</li>
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</ul>
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<li class="tocline2"><a href="#specificity">9. Calculating a selector's specificity</a>
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<li class="tocline2"><a href="#w3cselgrammar">10. The grammar of Selectors</a>
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<ul class="toc">
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<li class="tocline3"><a href="#grammar">10.1. Grammar</a>
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<li class="tocline3"><a href="#lex">10.2. Lexical scanner</a></li>
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</ul>
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<li class="tocline2"><a href="#downlevel">11. Namespaces and down-level clients</a>
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<li class="tocline2"><a href="#profiling">12. Profiles</a>
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<li><a href="#Conformance">13. Conformance and requirements</a>
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<li><a href="#Tests">14. Tests</a>
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<li><a href="#ACKS">15. Acknowledgements</a>
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<li class="tocline2"><a href="#references">16. References</a>
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</ul>
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</div>
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<h2><a name=context>1. Introduction</a></h2>
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<h3><a name=dependencies></a>1.1. Dependencies</h3>
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<p>Some features of this specification are specific to CSS, or have
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particular limitations or rules specific to CSS. In this
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specification, these have been described in terms of CSS2.1. <a
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href="#refsCSS21">[CSS21]</a></p>
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<h3><a name=terminology></a>1.2. Terminology</h3>
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<p>All of the text of this specification is normative except
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examples, notes, and sections explicitly marked as
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non-normative.</p>
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<h3><a name=changesFromCSS2></a>1.3. Changes from CSS2</h3>
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<p><em>This section is non-normative.</em></p>
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<p>The main differences between the selectors in CSS2 and those in
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Selectors are:
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<ul>
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<li>the list of basic definitions (selector, group of selectors,
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simple selector, etc.) has been changed; in particular, what was
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referred to in CSS2 as a simple selector is now called a sequence
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of simple selectors, and the term "simple selector" is now used for
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the components of this sequence</li>
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<li>an optional namespace component is now allowed in type element
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selectors, the universal selector and attribute selectors</li>
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<li>a <a href="#general-sibling-combinators">new combinator</a> has been introduced</li>
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<li>new simple selectors including substring matching attribute
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selectors, and new pseudo-classes</li>
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<li>new pseudo-elements, and introduction of the "::" convention
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for pseudo-elements</li>
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<li>the grammar has been rewritten</li>
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<li>profiles to be added to specifications integrating Selectors
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and defining the set of selectors which is actually supported by
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each specification</li>
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<li>Selectors are now a CSS3 Module and an independent
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specification; other specifications can now refer to this document
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independently of CSS</li>
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<li>the specification now has its own test suite</li>
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</ul>
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<h2><a name=selectors></a>2. Selectors</h2>
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<p><em>This section is non-normative, as it merely summarizes the
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following sections.</em></p>
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<p>A Selector represents a structure. This structure can be used as a
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condition (e.g. in a CSS rule) that determines which elements a
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selector matches in the document tree, or as a flat description of the
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HTML or XML fragment corresponding to that structure.</p>
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<p>Selectors may range from simple element names to rich contextual
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representations.</p>
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<p>The following table summarizes the Selector syntax:</p>
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<table class="selectorsReview">
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<thead>
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<tr>
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<th class="pattern">Pattern</th>
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<th class="meaning">Meaning</th>
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<th class="described">Described in section</th>
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<th class="origin">First defined in CSS level</th></tr>
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<tbody>
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<tr>
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<td class="pattern">*</td>
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<td class="meaning">any element</td>
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<td class="described"><a
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href="#universal-selector">Universal
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selector</a></td>
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<td class="origin">2</td></tr>
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<tr>
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<td class="pattern">E</td>
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<td class="meaning">an element of type E</td>
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<td class="described"><a
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href="#type-selectors">Type selector</a></td>
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<td class="origin">1</td></tr>
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<tr>
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<td class="pattern">E[foo]</td>
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<td class="meaning">an E element with a "foo" attribute</td>
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<td class="described"><a
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href="#attribute-selectors">Attribute
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selectors</a></td>
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<td class="origin">2</td></tr>
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<tr>
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<td class="pattern">E[foo="bar"]</td>
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<td class="meaning">an E element whose "foo" attribute value is exactly
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equal to "bar"</td>
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<td class="described"><a
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href="#attribute-selectors">Attribute
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selectors</a></td>
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<td class="origin">2</td></tr>
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<tr>
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<td class="pattern">E[foo~="bar"]</td>
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<td class="meaning">an E element whose "foo" attribute value is a list of
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space-separated values, one of which is exactly equal to "bar"</td>
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<td class="described"><a
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href="#attribute-selectors">Attribute
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selectors</a></td>
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<td class="origin">2</td></tr>
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<tr>
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<td class="pattern">E[foo^="bar"]</td>
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<td class="meaning">an E element whose "foo" attribute value begins exactly
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with the string "bar"</td>
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<td class="described"><a
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href="#attribute-selectors">Attribute
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selectors</a></td>
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<td class="origin">3</td></tr>
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<tr>
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<td class="pattern">E[foo$="bar"]</td>
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<td class="meaning">an E element whose "foo" attribute value ends exactly
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with the string "bar"</td>
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<td class="described"><a
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href="#attribute-selectors">Attribute
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selectors</a></td>
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<td class="origin">3</td></tr>
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<tr>
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<td class="pattern">E[foo*="bar"]</td>
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<td class="meaning">an E element whose "foo" attribute value contains the
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substring "bar"</td>
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<td class="described"><a
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href="#attribute-selectors">Attribute
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selectors</a></td>
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<td class="origin">3</td></tr>
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<tr>
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<td class="pattern">E[hreflang|="en"]</td>
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<td class="meaning">an E element whose "hreflang" attribute has a hyphen-separated
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list of values beginning (from the left) with "en"</td>
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<td class="described"><a
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href="#attribute-selectors">Attribute
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selectors</a></td>
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<td class="origin">2</td></tr>
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<tr>
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<td class="pattern">E:root</td>
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<td class="meaning">an E element, root of the document</td>
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<td class="described"><a
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href="#structural-pseudos">Structural
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pseudo-classes</a></td>
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<td class="origin">3</td></tr>
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<tr>
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<td class="pattern">E:nth-child(n)</td>
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<td class="meaning">an E element, the n-th child of its parent</td>
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<td class="described"><a
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href="#structural-pseudos">Structural
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pseudo-classes</a></td>
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<td class="origin">3</td></tr>
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<tr>
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<td class="pattern">E:nth-last-child(n)</td>
|
|
<td class="meaning">an E element, the n-th child of its parent, counting
|
|
from the last one</td>
|
|
<td class="described"><a
|
|
href="#structural-pseudos">Structural
|
|
pseudo-classes</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:nth-of-type(n)</td>
|
|
<td class="meaning">an E element, the n-th sibling of its type</td>
|
|
<td class="described"><a
|
|
href="#structural-pseudos">Structural
|
|
pseudo-classes</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:nth-last-of-type(n)</td>
|
|
<td class="meaning">an E element, the n-th sibling of its type, counting
|
|
from the last one</td>
|
|
<td class="described"><a
|
|
href="#structural-pseudos">Structural
|
|
pseudo-classes</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:first-child</td>
|
|
<td class="meaning">an E element, first child of its parent</td>
|
|
<td class="described"><a
|
|
href="#structural-pseudos">Structural
|
|
pseudo-classes</a></td>
|
|
<td class="origin">2</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:last-child</td>
|
|
<td class="meaning">an E element, last child of its parent</td>
|
|
<td class="described"><a
|
|
href="#structural-pseudos">Structural
|
|
pseudo-classes</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:first-of-type</td>
|
|
<td class="meaning">an E element, first sibling of its type</td>
|
|
<td class="described"><a
|
|
href="#structural-pseudos">Structural
|
|
pseudo-classes</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:last-of-type</td>
|
|
<td class="meaning">an E element, last sibling of its type</td>
|
|
<td class="described"><a
|
|
href="#structural-pseudos">Structural
|
|
pseudo-classes</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:only-child</td>
|
|
<td class="meaning">an E element, only child of its parent</td>
|
|
<td class="described"><a
|
|
href="#structural-pseudos">Structural
|
|
pseudo-classes</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:only-of-type</td>
|
|
<td class="meaning">an E element, only sibling of its type</td>
|
|
<td class="described"><a
|
|
href="#structural-pseudos">Structural
|
|
pseudo-classes</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:empty</td>
|
|
<td class="meaning">an E element that has no children (including text
|
|
nodes)</td>
|
|
<td class="described"><a
|
|
href="#structural-pseudos">Structural
|
|
pseudo-classes</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:link<br>E:visited</td>
|
|
<td class="meaning">an E element being the source anchor of a hyperlink of
|
|
which the target is not yet visited (:link) or already visited
|
|
(:visited)</td>
|
|
<td class="described"><a
|
|
href="#link">The link
|
|
pseudo-classes</a></td>
|
|
<td class="origin">1</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:active<br>E:hover<br>E:focus</td>
|
|
<td class="meaning">an E element during certain user actions</td>
|
|
<td class="described"><a
|
|
href="#useraction-pseudos">The user
|
|
action pseudo-classes</a></td>
|
|
<td class="origin">1 and 2</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:target</td>
|
|
<td class="meaning">an E element being the target of the referring URI</td>
|
|
<td class="described"><a
|
|
href="#target-pseudo">The target
|
|
pseudo-class</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:lang(fr)</td>
|
|
<td class="meaning">an element of type E in language "fr" (the document
|
|
language specifies how language is determined)</td>
|
|
<td class="described"><a
|
|
href="#lang-pseudo">The :lang()
|
|
pseudo-class</a></td>
|
|
<td class="origin">2</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:enabled<br>E:disabled</td>
|
|
<td class="meaning">a user interface element E which is enabled or
|
|
disabled</td>
|
|
<td class="described"><a
|
|
href="#UIstates">The UI element states
|
|
pseudo-classes</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:checked<!--<br>E:indeterminate--></td>
|
|
<td class="meaning">a user interface element E which is checked<!-- or in an
|
|
indeterminate state--> (for instance a radio-button or checkbox)</td>
|
|
<td class="described"><a
|
|
href="#UIstates">The UI element states
|
|
pseudo-classes</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E::first-line</td>
|
|
<td class="meaning">the first formatted line of an E element</td>
|
|
<td class="described"><a
|
|
href="#first-line">The ::first-line
|
|
pseudo-element</a></td>
|
|
<td class="origin">1</td></tr>
|
|
<tr>
|
|
<td class="pattern">E::first-letter</td>
|
|
<td class="meaning">the first formatted letter of an E element</td>
|
|
<td class="described"><a
|
|
href="#first-letter">The ::first-letter
|
|
pseudo-element</a></td>
|
|
<td class="origin">1</td></tr>
|
|
<tr>
|
|
<td class="pattern">E::selection</td>
|
|
<td class="meaning">the portion of an E element that is currently
|
|
selected/highlighted by the user</td>
|
|
<td class="described"><a
|
|
href="#UIfragments">The UI element
|
|
fragments pseudo-elements</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E::before</td>
|
|
<td class="meaning">generated content before an E element</td>
|
|
<td class="described"><a
|
|
href="#gen-content">The ::before
|
|
pseudo-element</a></td>
|
|
<td class="origin">2</td></tr>
|
|
<tr>
|
|
<td class="pattern">E::after</td>
|
|
<td class="meaning">generated content after an E element</td>
|
|
<td class="described"><a
|
|
href="#gen-content">The ::after
|
|
pseudo-element</a></td>
|
|
<td class="origin">2</td></tr>
|
|
<tr>
|
|
<td class="pattern">E.warning</td>
|
|
<td class="meaning">an E element whose class is
|
|
"warning" (the document language specifies how class is determined).</td>
|
|
<td class="described"><a
|
|
href="#class-html">Class
|
|
selectors</a></td>
|
|
<td class="origin">1</td></tr>
|
|
<tr>
|
|
<td class="pattern">E#myid</td>
|
|
<td class="meaning">an E element with ID equal to "myid".</td>
|
|
<td class="described"><a
|
|
href="#id-selectors">ID
|
|
selectors</a></td>
|
|
<td class="origin">1</td></tr>
|
|
<tr>
|
|
<td class="pattern">E:not(s)</td>
|
|
<td class="meaning">an E element that does not match simple selector s</td>
|
|
<td class="described"><a
|
|
href="#negation">Negation
|
|
pseudo-class</a></td>
|
|
<td class="origin">3</td></tr>
|
|
<tr>
|
|
<td class="pattern">E F</td>
|
|
<td class="meaning">an F element descendant of an E element</td>
|
|
<td class="described"><a
|
|
href="#descendant-combinators">Descendant
|
|
combinator</a></td>
|
|
<td class="origin">1</td></tr>
|
|
<tr>
|
|
<td class="pattern">E > F</td>
|
|
<td class="meaning">an F element child of an E element</td>
|
|
<td class="described"><a
|
|
href="#child-combinators">Child
|
|
combinator</a></td>
|
|
<td class="origin">2</td></tr>
|
|
<tr>
|
|
<td class="pattern">E + F</td>
|
|
<td class="meaning">an F element immediately preceded by an E element</td>
|
|
<td class="described"><a
|
|
href="#adjacent-sibling-combinators">Adjacent sibling combinator</a></td>
|
|
<td class="origin">2</td></tr>
|
|
<tr>
|
|
<td class="pattern">E ~ F</td>
|
|
<td class="meaning">an F element preceded by an E element</td>
|
|
<td class="described"><a
|
|
href="#general-sibling-combinators">General sibling combinator</a></td>
|
|
<td class="origin">3</td></tr></tbody></table>
|
|
|
|
<p>The meaning of each selector is derived from the table above by
|
|
prepending "matches" to the contents of each cell in the "Meaning"
|
|
column.</p>
|
|
|
|
<h2><a name=casesens>3. Case sensitivity</a></h2>
|
|
|
|
<p>The case sensitivity of document language element names, attribute
|
|
names, and attribute values in selectors depends on the document
|
|
language. For example, in HTML, element names are case-insensitive,
|
|
but in XML, they are case-sensitive.</p>
|
|
|
|
<h2><a name=selector-syntax>4. Selector syntax</a></h2>
|
|
|
|
<p>A <dfn><a name=selector>selector</a></dfn> is a chain of one
|
|
or more <a href="#sequence">sequences of simple selectors</a>
|
|
separated by <a href="#combinators">combinators</a>.</p>
|
|
|
|
<p>A <dfn><a name=sequence>sequence of simple selectors</a></dfn>
|
|
is a chain of <a href="#simple-selectors-dfn">simple selectors</a>
|
|
that are not separated by a <a href="#combinators">combinator</a>. It
|
|
always begins with a <a href="#type-selectors">type selector</a> or a
|
|
<a href="#universal-selector">universal selector</a>. No other type
|
|
selector or universal selector is allowed in the sequence.</p>
|
|
|
|
<p>A <dfn><a name=simple-selectors-dfn></a><a
|
|
href="#simple-selectors">simple selector</a></dfn> is either a <a
|
|
href="#type-selectors">type selector</a>, <a
|
|
href="#universal-selector">universal selector</a>, <a
|
|
href="#attribute-selectors">attribute selector</a>, <a
|
|
href="#class-html">class selector</a>, <a
|
|
href="#id-selectors">ID selector</a>, <a
|
|
href="#content-selectors">content selector</a>, or <a
|
|
href="#pseudo-classes">pseudo-class</a>. One <a
|
|
href="#pseudo-elements">pseudo-element</a> may be appended to the last
|
|
sequence of simple selectors.</p>
|
|
|
|
<p><dfn>Combinators</dfn> are: white space, "greater-than
|
|
sign" (U+003E, <code>></code>), "plus sign" (U+002B,
|
|
<code>+</code>) and "tilde" (U+007E, <code>~</code>). White
|
|
space may appear between a combinator and the simple selectors around
|
|
it. <a name=whitespace></a>Only the characters "space" (U+0020), "tab"
|
|
(U+0009), "line feed" (U+000A), "carriage return" (U+000D), and "form
|
|
feed" (U+000C) can occur in white space. Other space-like characters,
|
|
such as "em-space" (U+2003) and "ideographic space" (U+3000), are
|
|
never part of white space.</p>
|
|
|
|
<p>The elements of a document tree that are represented by a selector
|
|
are the <dfn><a name=subject></a>subjects of the selector</dfn>. A
|
|
selector consisting of a single sequence of simple selectors
|
|
represents any element satisfying its requirements. Prepending another
|
|
sequence of simple selectors and a combinator to a sequence imposes
|
|
additional matching constraints, so the subjects of a selector are
|
|
always a subset of the elements represented by the last sequence of
|
|
simple selectors.</p>
|
|
|
|
<p>An empty selector, containing no sequence of simple selectors and
|
|
no pseudo-element, is an <a href="#Conformance">invalid
|
|
selector</a>.</p>
|
|
|
|
<h2><a name=grouping>5. Groups of selectors</a></h2>
|
|
|
|
<p>When several selectors share the same declarations, they may be
|
|
grouped into a comma-separated list. (A comma is U+002C.)</p>
|
|
|
|
<div class="example">
|
|
<p>CSS examples:</p>
|
|
<p>In this example, we condense three rules with identical
|
|
declarations into one. Thus,</p>
|
|
<pre>h1 { font-family: sans-serif }
|
|
h2 { font-family: sans-serif }
|
|
h3 { font-family: sans-serif }</pre>
|
|
<p>is equivalent to:</p>
|
|
<pre>h1, h2, h3 { font-family: sans-serif }</pre>
|
|
</div>
|
|
|
|
<p><strong>Warning</strong>: the equivalence is true in this example
|
|
because all the selectors are valid selectors. If just one of these
|
|
selectors were invalid, the entire group of selectors would be
|
|
invalid. This would invalidate the rule for all three heading
|
|
elements, whereas in the former case only one of the three individual
|
|
heading rules would be invalidated.</p>
|
|
|
|
|
|
<h2><a name=simple-selectors>6. Simple selectors</a></h2>
|
|
|
|
<h3><a name=type-selectors>6.1. Type selector</a></h3>
|
|
|
|
<p>A <dfn>type selector</dfn> is the name of a document language
|
|
element type. A type selector represents an instance of the element
|
|
type in the document tree.</p>
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<p>The following selector represents an <code>h1</code> element in the document tree:</p>
|
|
<pre>h1</pre>
|
|
</div>
|
|
|
|
|
|
<h4><a name=typenmsp>6.1.1. Type selectors and namespaces</a></h4>
|
|
|
|
<p>Type selectors allow an optional namespace (<a
|
|
href="#refsXMLNAMES">[XMLNAMES]</a>) component. A namespace prefix
|
|
that has been previously declared may be prepended to the element name
|
|
separated by the namespace separator "vertical bar"
|
|
(U+007C, <code>|</code>).</p>
|
|
|
|
<p>The namespace component may be left empty to indicate that the
|
|
selector is only to represent elements with no declared namespace.</p>
|
|
|
|
<p>An asterisk may be used for the namespace prefix, indicating that
|
|
the selector represents elements in any namespace (including elements
|
|
with no namespace).</p>
|
|
|
|
<p>Element type selectors that have no namespace component (no
|
|
namespace separator), represent elements without regard to the
|
|
element's namespace (equivalent to "<code>*|</code>") unless a default
|
|
namespace has been declared. If a default namespace has been declared,
|
|
the selector will represent only elements in the default
|
|
namespace.</p>
|
|
|
|
<p>A type selector containing a namespace prefix that has not been
|
|
previously declared is an <a href="#Conformance">invalid</a> selector.
|
|
The mechanism for declaring a namespace prefix is left up to the
|
|
language implementing Selectors. In CSS, such a mechanism is defined
|
|
in the General Syntax module.</p>
|
|
|
|
<p>In a namespace-aware client, element type selectors will only match
|
|
against the <a
|
|
href="http://www.w3.org/TR/REC-xml-names/#NT-LocalPart">local part</a>
|
|
of the element's <a
|
|
href="http://www.w3.org/TR/REC-xml-names/#ns-qualnames">qualified
|
|
name</a>. See <a href="#downlevel">below</a> for notes about matching
|
|
behaviors in down-level clients.</p>
|
|
|
|
<p>In summary:</p>
|
|
|
|
<dl>
|
|
<dt><code>ns|E</code></dt>
|
|
<dd>elements with name E in namespace ns</dd>
|
|
<dt><code>*|E</code></dt>
|
|
<dd>elements with name E in any namespace, including those without any
|
|
declared namespace</dd>
|
|
<dt><code>|E</code></dt>
|
|
<dd>elements with name E without any declared namespace</dd>
|
|
<dt><code>E</code></dt>
|
|
<dd>if no default namespace has been specified, this is equivalent to *|E.
|
|
Otherwise it is equivalent to ns|E where ns is the default namespace.</dd>
|
|
</dl>
|
|
|
|
<div class="example">
|
|
<p>CSS examples:</p>
|
|
|
|
<pre>@namespace foo url(http://www.example.com);
|
|
foo|h1 { color: blue }
|
|
foo|* { color: yellow }
|
|
|h1 { color: red }
|
|
*|h1 { color: green }
|
|
h1 { color: green }</pre>
|
|
|
|
<p>The first rule will match only <code>h1</code> elements in the
|
|
"http://www.example.com" namespace.</p>
|
|
|
|
<p>The second rule will match all elements in the
|
|
"http://www.example.com" namespace.</p>
|
|
|
|
<p>The third rule will match only <code>h1</code> elements without
|
|
any declared namespace.</p>
|
|
|
|
<p>The fourth rule will match <code>h1</code> elements in any
|
|
namespace (including those without any declared namespace).</p>
|
|
|
|
<p>The last rule is equivalent to the fourth rule because no default
|
|
namespace has been defined.</p>
|
|
|
|
</div>
|
|
|
|
<h3><a name=universal-selector>6.2. Universal selector</a> </h3>
|
|
|
|
<p>The <dfn>universal selector</dfn>, written "asterisk"
|
|
(<code>*</code>), represents the qualified name of any element
|
|
type. It represents any single element in the document tree in any
|
|
namespace (including those without any declared namespace) if no
|
|
default namespace has been specified. If a default namespace has been
|
|
specified, see <a href="#univnmsp">Universal selector and
|
|
Namespaces</a> below.</p>
|
|
|
|
<p>If the universal selector is not the only component of a sequence
|
|
of simple selectors, the <code>*</code> may be omitted.</p>
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<ul>
|
|
<li><code>*[hreflang|=en]</code> and <code>[hreflang|=en]</code> are equivalent,</li>
|
|
<li><code>*.warning</code> and <code>.warning</code> are equivalent,</li>
|
|
<li><code>*#myid</code> and <code>#myid</code> are equivalent.</li>
|
|
</ul>
|
|
</div>
|
|
|
|
<p class="note"><strong>Note:</strong> it is recommended that the
|
|
<code>*</code>, representing the universal selector, not be
|
|
omitted.</p>
|
|
|
|
<h4><a name=univnmsp>6.2.1. Universal selector and namespaces</a></h4>
|
|
|
|
<p>The universal selector allows an optional namespace component. It
|
|
is used as follows:</p>
|
|
|
|
<dl>
|
|
<dt><code>ns|*</code></dt>
|
|
<dd>all elements in namespace ns</dd>
|
|
<dt><code>*|*</code></dt>
|
|
<dd>all elements</dd>
|
|
<dt><code>|*</code></dt>
|
|
<dd>all elements without any declared namespace</dd>
|
|
<dt><code>*</code></dt>
|
|
<dd>if no default namespace has been specified, this is equivalent to *|*.
|
|
Otherwise it is equivalent to ns|* where ns is the default namespace.</dd>
|
|
</dl>
|
|
|
|
<p>A universal selector containing a namespace prefix that has not
|
|
been previously declared is an <a href="#Conformance">invalid</a>
|
|
selector. The mechanism for declaring a namespace prefix is left up
|
|
to the language implementing Selectors. In CSS, such a mechanism is
|
|
defined in the General Syntax module.</p>
|
|
|
|
|
|
<h3><a name=attribute-selectors>6.3. Attribute selectors</a></h3>
|
|
|
|
<p>Selectors allow the representation of an element's attributes. When
|
|
a selector is used as an expression to match against an element,
|
|
attribute selectors must be considered to match an element if that
|
|
element has an attribute that matches the attribute represented by the
|
|
attribute selector.</p>
|
|
|
|
<h4><a name=attribute-representation>6.3.1. Attribute presence and values
|
|
selectors</a></h4>
|
|
|
|
<p>CSS2 introduced four attribute selectors:</p>
|
|
|
|
<dl>
|
|
<dt><code>[att]</code>
|
|
<dd>Represents an element with the <code>att</code> attribute, whatever the value of
|
|
the attribute.</dd>
|
|
<dt><code>[att=val]</code></dt>
|
|
<dd>Represents an element with the <code>att</code> attribute whose value is exactly
|
|
"val".</dd>
|
|
<dt><code>[att~=val]</code></dt>
|
|
<dd>Represents an element with the <code>att</code> attribute whose value is a <a
|
|
href="#whitespace">whitespace</a>-separated list of words, one of
|
|
which is exactly "val". If "val" contains whitespace, it will never
|
|
represent anything (since the words are <em>separated</em> by
|
|
spaces).</dd>
|
|
<dt><code>[att|=val]</code>
|
|
<dd>Represents an element with the <code>att</code> attribute, its value either
|
|
being exactly "val" or beginning with "val" immediately followed by
|
|
"-" (U+002D). This is primarily intended to allow language subcode
|
|
matches (e.g., the <code>hreflang</code> attribute on the
|
|
<code>link</code> element in HTML) as described in RFC 3066 (<a
|
|
href="#refsRFC3066">[RFC3066]</a>). For <code>lang</code> (or
|
|
<code>xml:lang</code>) language subcode matching, please see <a
|
|
href="#lang-pseudo">the <code>:lang</code> pseudo-class</a>.</dd>
|
|
</dl>
|
|
|
|
<p>Attribute values must be identifiers or strings. The
|
|
case-sensitivity of attribute names and values in selectors depends on
|
|
the document language.</p>
|
|
|
|
<div class="example">
|
|
|
|
<p>Examples:</p>
|
|
|
|
<p>The following attribute selector represents an <code>h1</code>
|
|
element that carries the <code>title</code> attribute, whatever its
|
|
value:</p>
|
|
|
|
<pre>h1[title]</pre>
|
|
|
|
<p>In the following example, the selector represents a
|
|
<code>span</code> element whose <code>class</code> attribute has
|
|
exactly the value "example":</p>
|
|
|
|
<pre>span[class="example"]</pre>
|
|
|
|
<p>Multiple attribute selectors can be used to represent several
|
|
attributes of an element, or several conditions on the same
|
|
attribute. Here, the selector represents a <code>span</code> element
|
|
whose <code>hello</code> attribute has exactly the value "Cleveland"
|
|
and whose <code>goodbye</code> attribute has exactly the value
|
|
"Columbus":</p>
|
|
|
|
<pre>span[hello="Cleveland"][goodbye="Columbus"]</pre>
|
|
|
|
<p>The following selectors illustrate the differences between "="
|
|
and "~=". The first selector will represent, for example, the value
|
|
"copyright copyleft copyeditor" on a <code>rel</code> attribute. The
|
|
second selector will only represent an <code>a</code> element with
|
|
an <code>href</code> attribute having the exact value
|
|
"http://www.w3.org/".</p>
|
|
|
|
<pre>a[rel~="copyright"]
|
|
a[href="http://www.w3.org/"]</pre>
|
|
|
|
<p>The following selector represents a <code>link</code> element
|
|
whose <code>hreflang</code> attribute is exactly "fr".</p>
|
|
|
|
<pre>link[hreflang=fr]</pre>
|
|
|
|
<p>The following selector represents a <code>link</code> element for
|
|
which the values of the <code>hreflang</code> attribute begins with
|
|
"en", including "en", "en-US", and "en-cockney":</p>
|
|
|
|
<pre>link[hreflang|="en"]</pre>
|
|
|
|
<p>Similarly, the following selectors represents a
|
|
<code>DIALOGUE</code> element whenever it has one of two different
|
|
values for an attribute <code>character</code>:</p>
|
|
|
|
<pre>DIALOGUE[character=romeo]
|
|
DIALOGUE[character=juliet]</pre>
|
|
|
|
</div>
|
|
|
|
<h4><a name=attribute-substrings></a>6.3.2. Substring matching attribute
|
|
selectors</h4>
|
|
|
|
<p>Three additional attribute selectors are provided for matching
|
|
substrings in the value of an attribute:</p>
|
|
|
|
<dl>
|
|
<dt><code>[att^=val]</code></dt>
|
|
<dd>Represents an element with the <code>att</code> attribute whose value begins
|
|
with the prefix "val".</dd>
|
|
<dt><code>[att$=val]</code>
|
|
<dd>Represents an element with the <code>att</code> attribute whose value ends with
|
|
the suffix "val".</dd>
|
|
<dt><code>[att*=val]</code>
|
|
<dd>Represents an element with the <code>att</code> attribute whose value contains
|
|
at least one instance of the substring "val".</dd>
|
|
</dl>
|
|
|
|
<p>Attribute values must be identifiers or strings. The
|
|
case-sensitivity of attribute names in selectors depends on the
|
|
document language.</p>
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<p>The following selector represents an HTML <code>object</code>, referencing an
|
|
image:</p>
|
|
<pre>object[type^="image/"]</pre>
|
|
<p>The following selector represents an HTML anchor <code>a</code> with an
|
|
<code>href</code> attribute whose value ends with ".html".</p>
|
|
<pre>a[href$=".html"]</pre>
|
|
<p>The following selector represents an HTML paragraph with a <code>title</code>
|
|
attribute whose value contains the substring "hello"</p>
|
|
<pre>p[title*="hello"]</pre>
|
|
</div>
|
|
|
|
<h4><a name=attrnmsp>6.3.3. Attribute selectors and namespaces</a></h4>
|
|
|
|
<p>Attribute selectors allow an optional namespace component to the
|
|
attribute name. A namespace prefix that has been previously declared
|
|
may be prepended to the attribute name separated by the namespace
|
|
separator "vertical bar" (<code>|</code>). In keeping with
|
|
the Namespaces in the XML recommendation, default namespaces do not
|
|
apply to attributes, therefore attribute selectors without a namespace
|
|
component apply only to attributes that have no declared namespace
|
|
(equivalent to "<code>|attr</code>"). An asterisk may be used for the
|
|
namespace prefix indicating that the selector is to match all
|
|
attribute names without regard to the attribute's namespace.
|
|
|
|
<p>An attribute selector with an attribute name containing a namespace
|
|
prefix that has not been previously declared is an <a
|
|
href="#Conformance">invalid</a> selector. The mechanism for declaring
|
|
a namespace prefix is left up to the language implementing Selectors.
|
|
In CSS, such a mechanism is defined in the General Syntax module.
|
|
|
|
<div class="example">
|
|
<p>CSS examples:</p>
|
|
<pre>@namespace foo "http://www.example.com";
|
|
[foo|att=val] { color: blue }
|
|
[*|att] { color: yellow }
|
|
[|att] { color: green }
|
|
[att] { color: green }</pre>
|
|
|
|
<p>The first rule will match only elements with the attribute
|
|
<code>att</code> in the "http://www.example.com" namespace with the
|
|
value "val".</p>
|
|
|
|
<p>The second rule will match only elements with the attribute
|
|
<code>att</code> regardless of the namespace of the attribute
|
|
(including no declared namespace).</p>
|
|
|
|
<p>The last two rules are equivalent and will match only elements
|
|
with the attribute <code>att</code> where the attribute is not
|
|
declared to be in a namespace.</p>
|
|
|
|
</div>
|
|
|
|
<h4><a name=def-values>6.3.4. Default attribute values in DTDs</a></h4>
|
|
|
|
<p>Attribute selectors represent explicitly set attribute values in
|
|
the document tree. Default attribute values may be defined in a DTD or
|
|
elsewhere, but cannot always be selected by attribute
|
|
selectors. Selectors should be designed so that they work even if the
|
|
default values are not included in the document tree.</p>
|
|
|
|
<p>More precisely, a UA is <em>not</em> required to read an "external
|
|
subset" of the DTD but <em>is</em> required to look for default
|
|
attribute values in the document's "internal subset." (See <a
|
|
href="#refsXML10">[XML10]</a> for definitions of these subsets.)</p>
|
|
|
|
<p>A UA that recognizes an XML namespace <a
|
|
href="#refsXMLNAMES">[XMLNAMES]</a> is not required to use its
|
|
knowledge of that namespace to treat default attribute values as if
|
|
they were present in the document. (For example, an XHTML UA is not
|
|
required to use its built-in knowledge of the XHTML DTD.)</p>
|
|
|
|
<p class="note"><strong>Note:</strong> Typically, implementations
|
|
choose to ignore external subsets.</p>
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
|
|
<p>Consider an element EXAMPLE with an attribute "notation" that has a
|
|
default value of "decimal". The DTD fragment might be</p>
|
|
|
|
<pre class="dtd-example"><!ATTLIST EXAMPLE notation (decimal,octal) "decimal"></pre>
|
|
|
|
<p>If the style sheet contains the rules</p>
|
|
|
|
<pre>EXAMPLE[notation=decimal] { /*... default property settings ...*/ }
|
|
EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
|
|
|
|
<p>the first rule will not match elements whose "notation" attribute
|
|
is set by default, i.e. not set explicitly. To catch all cases, the
|
|
attribute selector for the default value must be dropped:</p>
|
|
|
|
<pre>EXAMPLE { /*... default property settings ...*/ }
|
|
EXAMPLE[notation=octal] { /*... other settings...*/ }</pre>
|
|
|
|
<p>Here, because the selector <code>EXAMPLE[notation=octal]</code> is
|
|
more specific than the tag
|
|
selector alone, the style declarations in the second rule will override
|
|
those in the first for elements that have a "notation" attribute value
|
|
of "octal". Care has to be taken that all property declarations that
|
|
are to apply only to the default case are overridden in the non-default
|
|
cases' style rules.</p>
|
|
|
|
</div>
|
|
|
|
<h3><a name=class-html>6.4. Class selectors</a></h3>
|
|
|
|
<p>Working with HTML, authors may use the period (U+002E,
|
|
<code>.</code>) notation as an alternative to the <code>~=</code>
|
|
notation when representing the <code>class</code> attribute. Thus, for
|
|
HTML, <code>div.value</code> and <code>div[class~=value]</code> have
|
|
the same meaning. The attribute value must immediately follow the
|
|
"period" (<code>.</code>).</p>
|
|
|
|
<p>UAs may apply selectors using the period (.) notation in XML
|
|
documents if the UA has namespace-specific knowledge that allows it to
|
|
determine which attribute is the "class" attribute for the
|
|
respective namespace. One such example of namespace-specific knowledge
|
|
is the prose in the specification for a particular namespace (e.g. SVG
|
|
1.0 <a href="#refsSVG">[SVG]</a> describes the <a
|
|
href="http://www.w3.org/TR/2001/PR-SVG-20010719/styling.html#ClassAttribute">SVG
|
|
"class" attribute</a> and how a UA should interpret it, and
|
|
similarly MathML 1.01 <a href="#refsMATH">[MATH]</a> describes the <a
|
|
href="http://www.w3.org/1999/07/REC-MathML-19990707/chapter2.html#sec2.3.4">MathML
|
|
"class" attribute</a>.)</p>
|
|
|
|
<div class="example">
|
|
<p>CSS examples:</p>
|
|
|
|
<p>We can assign style information to all elements with
|
|
<code>class~="pastoral"</code> as follows:</p>
|
|
|
|
<pre>*.pastoral { color: green } /* all elements with class~=pastoral */</pre>
|
|
|
|
<p>or just</p>
|
|
|
|
<pre>.pastoral { color: green } /* all elements with class~=pastoral */</pre>
|
|
|
|
<p>The following assigns style only to H1 elements with
|
|
<code>class~="pastoral"</code>:</p>
|
|
|
|
<pre>H1.pastoral { color: green } /* H1 elements with class~=pastoral */</pre>
|
|
|
|
<p>Given these rules, the first H1 instance below would not have
|
|
green text, while the second would:</p>
|
|
|
|
<pre><H1>Not green</H1>
|
|
<H1 class="pastoral">Very green</H1></pre>
|
|
|
|
</div>
|
|
|
|
<p>To represent a subset of "class" values, each value must be preceded
|
|
by a ".", in any order.</P>
|
|
|
|
<div class="example">
|
|
|
|
<p>CSS example:</p>
|
|
|
|
<p>The following rule matches any P element whose "class" attribute
|
|
has been assigned a list of <a
|
|
href="#whitespace">whitespace</a>-separated values that includes
|
|
"pastoral" and "marine":</p>
|
|
|
|
<pre>p.pastoral.marine { color: green }</pre>
|
|
|
|
<p>This rule matches when <code>class="pastoral blue aqua
|
|
marine"</code> but does not match for <code>class="pastoral
|
|
blue"</code>.</p>
|
|
|
|
</div>
|
|
|
|
<p class="note"><strong>Note:</strong> Because CSS gives considerable
|
|
power to the "class" attribute, authors could conceivably design their
|
|
own "document language" based on elements with almost no associated
|
|
presentation (such as DIV and SPAN in HTML) and assigning style
|
|
information through the "class" attribute. Authors should avoid this
|
|
practice since the structural elements of a document language often
|
|
have recognized and accepted meanings and author-defined classes may
|
|
not.</p>
|
|
|
|
<p class="note"><strong>Note:</strong> If an element has multiple
|
|
class attributes, their values must be concatenated with spaces
|
|
between the values before searching for the class. As of this time the
|
|
working group is not aware of any manner in which this situation can
|
|
be reached, however, so this behavior is explicitly non-normative in
|
|
this specification.</p>
|
|
|
|
<h3><a name=id-selectors>6.5. ID selectors</a></h3>
|
|
|
|
<p>Document languages may contain attributes that are declared to be
|
|
of type ID. What makes attributes of type ID special is that no two
|
|
such attributes can have the same value in a document, regardless of
|
|
the type of the elements that carry them; whatever the document
|
|
language, an ID typed attribute can be used to uniquely identify its
|
|
element. In HTML all ID attributes are named "id"; XML applications
|
|
may name ID attributes differently, but the same restriction
|
|
applies.</p>
|
|
|
|
<p>An ID-typed attribute of a document language allows authors to
|
|
assign an identifier to one element instance in the document tree. W3C
|
|
ID selectors represent an element instance based on its identifier. An
|
|
ID selector contains a "number sign" (U+0023,
|
|
<code>#</code>) immediately followed by the ID value, which must be an
|
|
identifier.</p>
|
|
|
|
<p>Selectors does not specify how a UA knows the ID-typed attribute of
|
|
an element. The UA may, e.g., read a document's DTD, have the
|
|
information hard-coded or ask the user.
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<p>The following ID selector represents an <code>h1</code> element
|
|
whose ID-typed attribute has the value "chapter1":</p>
|
|
<pre>h1#chapter1</pre>
|
|
<p>The following ID selector represents any element whose ID-typed
|
|
attribute has the value "chapter1":</p>
|
|
<pre>#chapter1</pre>
|
|
<p>The following selector represents any element whose ID-typed
|
|
attribute has the value "z98y".</p>
|
|
<pre>*#z98y</pre>
|
|
</div>
|
|
|
|
<p class="note"><strong>Note.</strong> In XML 1.0 <a
|
|
href="#refsXML10">[XML10]</a>, the information about which attribute
|
|
contains an element's IDs is contained in a DTD or a schema. When
|
|
parsing XML, UAs do not always read the DTD, and thus may not know
|
|
what the ID of an element is (though a UA may have namespace-specific
|
|
knowledge that allows it to determine which attribute is the ID
|
|
attribute for that namespace). If a style sheet designer knows or
|
|
suspects that a UA may not know what the ID of an element is, he
|
|
should use normal attribute selectors instead:
|
|
<code>[name=p371]</code> instead of <code>#p371</code>. Elements in
|
|
XML 1.0 documents without a DTD do not have IDs at all.</p>
|
|
|
|
<p>If an element has multiple ID attributes, all of them must be
|
|
treated as IDs for that element for the purposes of the ID
|
|
selector. Such a situation could be reached using mixtures of xml:id,
|
|
DOM3 Core, XML DTDs, and namespace-specific knowledge.</p>
|
|
|
|
<h3><a name=pseudo-classes>6.6. Pseudo-classes</a></h3>
|
|
|
|
<p>The pseudo-class concept is introduced to permit selection based on
|
|
information that lies outside of the document tree or that cannot be
|
|
expressed using the other simple selectors.</p>
|
|
|
|
<p>A pseudo-class always consists of a "colon"
|
|
(<code>:</code>) followed by the name of the pseudo-class and
|
|
optionally by a value between parentheses.</p>
|
|
|
|
<p>Pseudo-classes are allowed in all sequences of simple selectors
|
|
contained in a selector. Pseudo-classes are allowed anywhere in
|
|
sequences of simple selectors, after the leading type selector or
|
|
universal selector (possibly omitted). Pseudo-class names are
|
|
case-insensitive. Some pseudo-classes are mutually exclusive, while
|
|
others can be applied simultaneously to the same
|
|
element. Pseudo-classes may be dynamic, in the sense that an element
|
|
may acquire or lose a pseudo-class while a user interacts with the
|
|
document.</p>
|
|
|
|
|
|
<h4><a name=dynamic-pseudos>6.6.1. Dynamic pseudo-classes</a></h4>
|
|
|
|
<p>Dynamic pseudo-classes classify elements on characteristics other
|
|
than their name, attributes, or content, in principle characteristics
|
|
that cannot be deduced from the document tree.</p>
|
|
|
|
<p>Dynamic pseudo-classes do not appear in the document source or
|
|
document tree.</p>
|
|
|
|
|
|
<h5>The <a name=link>link pseudo-classes: :link and :visited</a></h5>
|
|
|
|
<p>User agents commonly display unvisited links differently from
|
|
previously visited ones. Selectors
|
|
provides the pseudo-classes <code>:link</code> and
|
|
<code>:visited</code> to distinguish them:</p>
|
|
|
|
<ul>
|
|
<li>The <code>:link</code> pseudo-class applies to links that have
|
|
not yet been visited.</li>
|
|
<li>The <code>:visited</code> pseudo-class applies once the link has
|
|
been visited by the user. </li>
|
|
</ul>
|
|
|
|
<p>After some amount of time, user agents may choose to return a
|
|
visited link to the (unvisited) ':link' state.</p>
|
|
|
|
<p>The two states are mutually exclusive.</p>
|
|
|
|
<div class="example">
|
|
|
|
<p>Example:</p>
|
|
|
|
<p>The following selector represents links carrying class
|
|
<code>external</code> and already visited:</p>
|
|
|
|
<pre>a.external:visited</pre>
|
|
|
|
</div>
|
|
|
|
<p class="note"><strong>Note:</strong> It is possible for style sheet
|
|
authors to abuse the :link and :visited pseudo-classes to determine
|
|
which sites a user has visited without the user's consent.
|
|
|
|
<p>UAs may therefore treat all links as unvisited links, or implement
|
|
other measures to preserve the user's privacy while rendering visited
|
|
and unvisited links differently.</p>
|
|
|
|
<h5>The <a name=useraction-pseudos>user action pseudo-classes
|
|
:hover, :active, and :focus</a></h5>
|
|
|
|
<p>Interactive user agents sometimes change the rendering in response
|
|
to user actions. Selectors provides
|
|
three pseudo-classes for the selection of an element the user is
|
|
acting on.</p>
|
|
|
|
<ul>
|
|
|
|
<li>The <code>:hover</code> pseudo-class applies while the user
|
|
designates an element with a pointing device, but does not activate
|
|
it. For example, a visual user agent could apply this pseudo-class
|
|
when the cursor (mouse pointer) hovers over a box generated by the
|
|
element. User agents not that do not support <a
|
|
href="http://www.w3.org/TR/REC-CSS2/media.html#interactive-media-group">interactive
|
|
media</a> do not have to support this pseudo-class. Some conforming
|
|
user agents that support <a
|
|
href="http://www.w3.org/TR/REC-CSS2/media.html#interactive-media-group">interactive
|
|
media</a> may not be able to support this pseudo-class (e.g., a pen
|
|
device that does not detect hovering).</li>
|
|
|
|
<li>The <code>:active</code> pseudo-class applies while an element
|
|
is being activated by the user. For example, between the times the
|
|
user presses the mouse button and releases it.</li>
|
|
|
|
<li>The <code>:focus</code> pseudo-class applies while an element
|
|
has the focus (accepts keyboard or mouse events, or other forms of
|
|
input). </li>
|
|
|
|
</ul>
|
|
|
|
<p>There may be document language or implementation specific limits on
|
|
which elements can become <code>:active</code> or acquire
|
|
<code>:focus</code>.</p>
|
|
|
|
<p>These pseudo-classes are not mutually exclusive. An element may
|
|
match several pseudo-classes at the same time.</p>
|
|
|
|
<p>Selectors doesn't define if the parent of an element that is
|
|
':active' or ':hover' is also in that state.</p>
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<pre>a:link /* unvisited links */
|
|
a:visited /* visited links */
|
|
a:hover /* user hovers */
|
|
a:active /* active links */</pre>
|
|
<p>An example of combining dynamic pseudo-classes:</p>
|
|
<pre>a:focus
|
|
a:focus:hover</pre>
|
|
<p>The last selector matches <code>a</code> elements that are in
|
|
the pseudo-class :focus and in the pseudo-class :hover.</p>
|
|
</div>
|
|
|
|
<p class="note"><strong>Note:</strong> An element can be both ':visited'
|
|
and ':active' (or ':link' and ':active').</p>
|
|
|
|
<h4><a name=target-pseudo>6.6.2. The target pseudo-class :target</a></h4>
|
|
|
|
<p>Some URIs refer to a location within a resource. This kind of URI
|
|
ends with a "number sign" (#) followed by an anchor
|
|
identifier (called the fragment identifier).</p>
|
|
|
|
<p>URIs with fragment identifiers link to a certain element within the
|
|
document, known as the target element. For instance, here is a URI
|
|
pointing to an anchor named <code>section_2</code> in an HTML
|
|
document:</p>
|
|
|
|
<pre>http://example.com/html/top.html#section_2</pre>
|
|
|
|
<p>A target element can be represented by the <code>:target</code>
|
|
pseudo-class. If the document's URI has no fragment identifier, then
|
|
the document has no target element.</p>
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<pre>p.note:target</pre>
|
|
<p>This selector represents a <code>p</code> element of class
|
|
<code>note</code> that is the target element of the referring
|
|
URI.</p>
|
|
</div>
|
|
|
|
<div class="example">
|
|
<p>CSS example:</p>
|
|
<p>Here, the <code>:target</code> pseudo-class is used to make the
|
|
target element red and place an image before it, if there is one:</p>
|
|
<pre>*:target { color : red }
|
|
*:target::before { content : url(target.png) }</pre>
|
|
</div>
|
|
|
|
<h4><a name=lang-pseudo>6.6.3. The language pseudo-class :lang</a></h4>
|
|
|
|
<p>If the document language specifies how the human language of an
|
|
element is determined, it is possible to write selectors that
|
|
represent an element based on its language. For example, in HTML <a
|
|
href="#refsHTML4">[HTML4]</a>, the language is determined by a
|
|
combination of the <code>lang</code> attribute, the <code>meta</code>
|
|
element, and possibly by information from the protocol (such as HTTP
|
|
headers). XML uses an attribute called <code>xml:lang</code>, and
|
|
there may be other document language-specific methods for determining
|
|
the language.</p>
|
|
|
|
<p>The pseudo-class <code>:lang(C)</code> represents an element that
|
|
is in language C. Whether an element is represented by a
|
|
<code>:lang()</code> selector is based solely on the identifier C
|
|
being either equal to, or a hyphen-separated substring of, the
|
|
element's language value, in the same way as if performed by the <a
|
|
href="#attribute-representation">'|='</a> operator in attribute
|
|
selectors. The identifier C does not have to be a valid language
|
|
name.</p>
|
|
|
|
<p>C must not be empty. (If it is, the selector is invalid.)</p>
|
|
|
|
<p class="note"><strong>Note:</strong> It is recommended that
|
|
documents and protocols indicate language using codes from RFC 3066 <a
|
|
href="#refsRFC3066">[RFC3066]</a> or its successor, and by means of
|
|
"xml:lang" attributes in the case of XML-based documents <a
|
|
href="#refsXML10">[XML10]</a>. See <a
|
|
href="http://www.w3.org/International/questions/qa-lang-2or3.html">
|
|
"FAQ: Two-letter or three-letter language codes."</a></p>
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<p>The two following selectors represent an HTML document that is in
|
|
Belgian, French, or German. The two next selectors represent
|
|
<code>q</code> quotations in an arbitrary element in Belgian, French,
|
|
or German.</p>
|
|
<pre>html:lang(fr-be)
|
|
html:lang(de)
|
|
:lang(fr-be) > q
|
|
:lang(de) > q</pre>
|
|
</div>
|
|
|
|
<h4><a name=UIstates>6.6.4. The UI element states pseudo-classes</a></h4>
|
|
|
|
<h5><a name=enableddisabled>The :enabled and :disabled pseudo-classes</a></h5>
|
|
|
|
<p>The <code>:enabled</code> pseudo-class allows authors to customize
|
|
the look of user interface elements that are enabled &mdart; which the
|
|
user can select or activate in some fashion (e.g. clicking on a button
|
|
with a mouse). There is a need for such a pseudo-class because there
|
|
is no way to programmatically specify the default appearance of say,
|
|
an enabled <code>input</code> element without also specifying what it
|
|
would look like when it was disabled.</p>
|
|
|
|
<p>Similar to <code>:enabled</code>, <code>:disabled</code> allows the
|
|
author to specify precisely how a disabled or inactive user interface
|
|
element should look.</p>
|
|
|
|
<p>Most elements will be neither enabled nor disabled. An element is
|
|
enabled if the user can either activate it or transfer the focus to
|
|
it. An element is disabled if it could be enabled, but the user cannot
|
|
presently activate it or transfer focus to it.</p>
|
|
|
|
|
|
<h5><a name=checked>The :checked pseudo-class</a></h5>
|
|
|
|
<p>Radio and checkbox elements can be toggled by the user. Some menu
|
|
items are "checked" when the user selects them. When such elements are
|
|
toggled "on" the <code>:checked</code> pseudo-class applies. The
|
|
<code>:checked</code> pseudo-class initially applies to such elements
|
|
that have the HTML4 <code>selected</code> and <code>checked</code>
|
|
attributes as described in <a
|
|
href="http://www.w3.org/TR/REC-html40/interact/forms.html#h-17.2.1">Section
|
|
17.2.1 of HTML4</a>, but of course the user can toggle "off" such
|
|
elements in which case the <code>:checked</code> pseudo-class would no
|
|
longer apply. While the <code>:checked</code> pseudo-class is dynamic
|
|
in nature, and is altered by user action, since it can also be based
|
|
on the presence of the semantic HTML4 <code>selected</code> and
|
|
<code>checked</code> attributes, it applies to all media.
|
|
|
|
|
|
<h5><a name=indeterminate>The :indeterminate pseudo-class</a></h5>
|
|
|
|
<div class="note">
|
|
|
|
<p>Radio and checkbox elements can be toggled by the user, but are
|
|
sometimes in an indeterminate state, neither checked nor unchecked.
|
|
This can be due to an element attribute, or DOM manipulation.</p>
|
|
|
|
<p>A future version of this specification may introduce an
|
|
<code>:indeterminate</code> pseudo-class that applies to such elements.
|
|
<!--While the <code>:indeterminate</code> pseudo-class is dynamic in
|
|
nature, and is altered by user action, since it can also be based on
|
|
the presence of an element attribute, it applies to all media.</p>
|
|
|
|
<p>Components of a radio-group initialized with no pre-selected choice
|
|
are an example of :indeterminate state.--></p>
|
|
|
|
</div>
|
|
|
|
|
|
<h4><a name=structural-pseudos>6.6.5. Structural pseudo-classes</a></h4>
|
|
|
|
<p>Selectors introduces the concept of <dfn>structural
|
|
pseudo-classes</dfn> to permit selection based on extra information that lies in
|
|
the document tree but cannot be represented by other simple selectors or
|
|
combinators.
|
|
|
|
<p>Note that standalone pieces of PCDATA (text nodes in the DOM) are
|
|
not counted when calculating the position of an element in the list of
|
|
children of its parent. When calculating the position of an element in
|
|
the list of children of its parent, the index numbering starts at 1.
|
|
|
|
|
|
<h5><a name=root-pseudo>:root pseudo-class</a></h5>
|
|
|
|
<p>The <code>:root</code> pseudo-class represents an element that is
|
|
the root of the document. In HTML 4, this is always the
|
|
<code>HTML</code> element.
|
|
|
|
|
|
<h5><a name=nth-child-pseudo>:nth-child() pseudo-class</a></h5>
|
|
|
|
<p>The
|
|
<code>:nth-child(<var>a</var><code>n</code>+<var>b</var>)</code>
|
|
pseudo-class notation represents an element that has
|
|
<var>a</var><code>n</code>+<var>b</var>-1 siblings
|
|
<strong>before</strong> it in the document tree, for a given positive
|
|
integer or zero value of <code>n</code>, and has a parent element. In
|
|
other words, this matches the <var>b</var>th child of an element after
|
|
all the children have been split into groups of <var>a</var> elements
|
|
each. For example, this allows the selectors to address every other
|
|
row in a table, and could be used to alternate the color
|
|
of paragraph text in a cycle of four. The <var>a</var> and
|
|
<var>b</var> values must be zero, negative integers or positive
|
|
integers. The index of the first child of an element is 1.
|
|
|
|
<p>In addition to this, <code>:nth-child()</code> can take
|
|
'<code>odd</code>' and '<code>even</code>' as arguments instead.
|
|
'<code>odd</code>' has the same signification as <code>2n+1</code>,
|
|
and '<code>even</code>' has the same signification as <code>2n</code>.
|
|
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<pre>tr:nth-child(2n+1) /* represents every odd row of an HTML table */
|
|
tr:nth-child(odd) /* same */
|
|
tr:nth-child(2n) /* represents every even row of an HTML table */
|
|
tr:nth-child(even) /* same */
|
|
|
|
/* Alternate paragraph colours in CSS */
|
|
p:nth-child(4n+1) { color: navy; }
|
|
p:nth-child(4n+2) { color: green; }
|
|
p:nth-child(4n+3) { color: maroon; }
|
|
p:nth-child(4n+4) { color: purple; }</pre>
|
|
</div>
|
|
|
|
<p>When <var>a</var>=0, no repeating is used, so for example
|
|
<code>:nth-child(0n+5)</code> matches only the fifth child. When
|
|
<var>a</var>=0, the <var>a</var><code>n</code> part need not be
|
|
included, so the syntax simplifies to
|
|
<code>:nth-child(<var>b</var>)</code> and the last example simplifies
|
|
to <code>:nth-child(5)</code>.
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<pre>foo:nth-child(0n+1) /* represents an element foo, first child of its parent element */
|
|
foo:nth-child(1) /* same */</pre>
|
|
</div>
|
|
|
|
<p>When <var>a</var>=1, the number may be omitted from the rule.
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<p>The following selectors are therefore equivalent:</p>
|
|
<pre>bar:nth-child(1n+0) /* represents all bar elements, specificity (0,1,1) */
|
|
bar:nth-child(n+0) /* same */
|
|
bar:nth-child(n) /* same */
|
|
bar /* same but lower specificity (0,0,1) */</pre>
|
|
</div>
|
|
|
|
<p>If <var>b</var>=0, then every <var>a</var>th element is picked. In
|
|
such a case, the <var>b</var> part may be omitted.
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<pre>tr:nth-child(2n+0) /* represents every even row of an HTML table */
|
|
tr:nth-child(2n) /* same */</pre>
|
|
</div>
|
|
|
|
<p>If both <var>a</var> and <var>b</var> are equal to zero, the
|
|
pseudo-class represents no element in the document tree.</p>
|
|
|
|
<p>The value <var>a</var> can be negative, but only the positive
|
|
values of <var>a</var><code>n</code>+<var>b</var>, for
|
|
<code>n</code>≥0, may represent an element in the document
|
|
tree.</p>
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<pre>html|tr:nth-child(-n+6) /* represents the 6 first rows of XHTML tables */</pre>
|
|
</div>
|
|
|
|
<p>When the value <var>b</var> is negative, the "+" character in the
|
|
expression must be removed (it is effectively replaced by the "-"
|
|
character indicating the negative value of <var>b</var>).</p>
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<pre>:nth-child(10n-1) /* represents the 9th, 19th, 29th, etc, element */
|
|
:nth-child(10n+9) /* Same */
|
|
:nth-child(10n+-1) /* Syntactically invalid, and would be ignored */</pre>
|
|
</div>
|
|
|
|
|
|
<h5><a name=nth-last-child-pseudo>:nth-last-child() pseudo-class</a></h5>
|
|
|
|
<p>The <code>:nth-last-child(<var>a</var>n+<var>b</var>)</code>
|
|
pseudo-class notation represents an element that has
|
|
<var>a</var><code>n</code>+<var>b</var>-1 siblings
|
|
<strong>after</strong> it in the document tree, for a given positive
|
|
integer or zero value of <code>n</code>, and has a parent element. See
|
|
<code>:nth-child()</code> pseudo-class for the syntax of its argument.
|
|
It also accepts the '<code>even</code>' and '<code>odd</code>' values
|
|
as arguments.
|
|
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<pre>tr:nth-last-child(-n+2) /* represents the two last rows of an HTML table */
|
|
|
|
foo:nth-last-child(odd) /* represents all odd foo elements in their parent element,
|
|
counting from the last one */</pre>
|
|
</div>
|
|
|
|
|
|
<h5><a name=nth-of-type-pseudo>:nth-of-type() pseudo-class</a></h5>
|
|
|
|
<p>The <code>:nth-of-type(<var>a</var>n+<var>b</var>)</code>
|
|
pseudo-class notation represents an element that has
|
|
<var>a</var><code>n</code>+<var>b</var>-1 siblings with the same
|
|
element name <strong>before</strong> it in the document tree, for a
|
|
given zero or positive integer value of <code>n</code>, and has a
|
|
parent element. In other words, this matches the <var>b</var>th child
|
|
of that type after all the children of that type have been split into
|
|
groups of a elements each. See <code>:nth-child()</code> pseudo-class
|
|
for the syntax of its argument. It also accepts the
|
|
'<code>even</code>' and '<code>odd</code>' values.
|
|
|
|
|
|
<div class="example">
|
|
<p>CSS example:</p>
|
|
<p>This allows an author to alternate the position of floated images:</p>
|
|
<pre>img:nth-of-type(2n+1) { float: right; }
|
|
img:nth-of-type(2n) { float: left; }</pre>
|
|
</div>
|
|
|
|
|
|
<h5><a name=nth-last-of-type-pseudo>:nth-last-of-type() pseudo-class</a></h5>
|
|
|
|
<p>The <code>:nth-last-of-type(<var>a</var>n+<var>b</var>)</code>
|
|
pseudo-class notation represents an element that has
|
|
<var>a</var><code>n</code>+<var>b</var>-1 siblings with the same
|
|
element name <strong>after</strong> it in the document tree, for a
|
|
given zero or positive integer value of <code>n</code>, and has a
|
|
parent element. See <code>:nth-child()</code> pseudo-class for the
|
|
syntax of its argument. It also accepts the '<code>even</code>' and '<code>odd</code>' values.
|
|
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<p>To represent all <code>h2</code> children of an XHTML
|
|
<code>body</code> except the first and last, one could use the
|
|
following selector:</p>
|
|
<pre>body > h2:nth-of-type(n+2):nth-last-of-type(n+2)</pre>
|
|
<p>In this case, one could also use <code>:not()</code>, although the
|
|
selector ends up being just as long:</p>
|
|
<pre>body > h2:not(:first-of-type):not(:last-of-type)</pre>
|
|
</div>
|
|
|
|
|
|
<h5><a name=first-child-pseudo>:first-child pseudo-class</a></h5>
|
|
|
|
<p>Same as <code>:nth-child(1)</code>. The <code>:first-child</code> pseudo-class
|
|
represents an element that is the first child of some other element.
|
|
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<p>The following selector represents a <code>p</code> element that is
|
|
the first child of a <code>div</code> element:</p>
|
|
<pre>div > p:first-child</pre>
|
|
<p>This selector can represent the <code>p</code> inside the
|
|
<code>div</code> of the following fragment:</p>
|
|
<pre><p> The last P before the note.</p>
|
|
<div class="note">
|
|
<p> The first P inside the note.</p>
|
|
</div></pre>but cannot represent the second <code>p</code> in the following
|
|
fragment:
|
|
<pre><p> The last P before the note.</p>
|
|
<div class="note">
|
|
<h2> Note </h2>
|
|
<p> The first P inside the note.</p>
|
|
</div></pre>
|
|
<p>The following two selectors are usually equivalent:</p>
|
|
<pre>* > a:first-child /* a is first child of any element */
|
|
a:first-child /* Same (assuming a is not the root element) */</pre>
|
|
</div>
|
|
|
|
<h5><a name=last-child-pseudo>:last-child pseudo-class</a></h5>
|
|
|
|
<p>Same as <code>:nth-last-child(1)</code>. The <code>:last-child</code> pseudo-class
|
|
represents an element that is the last child of some other element.
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<p>The following selector represents a list item <code>li</code> that
|
|
is the last child of an ordered list <code>ol</code>.
|
|
<pre>ol > li:last-child</pre>
|
|
</div>
|
|
|
|
<h5><a name=first-of-type-pseudo>:first-of-type pseudo-class</a></h5>
|
|
|
|
<p>Same as <code>:nth-of-type(1)</code>. The <code>:first-of-type</code> pseudo-class
|
|
represents an element that is the first sibling of its type in the list of
|
|
children of its parent element.
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<p>The following selector represents a definition title
|
|
<code>dt</code> inside a definition list <code>dl</code>, this
|
|
<code>dt</code> being the first of its type in the list of children of
|
|
its parent element.</p>
|
|
<pre>dl dt:first-of-type</pre>
|
|
<p>It is a valid description for the first two <code>dt</code>
|
|
elements in the following example but not for the third one:</p>
|
|
<pre><dl>
|
|
<dt>gigogne</dt>
|
|
<dd>
|
|
<dl>
|
|
<dt>fusée</dt>
|
|
<dd>multistage rocket</dd>
|
|
<dt>table</dt>
|
|
<dd>nest of tables</dd>
|
|
</dl>
|
|
</dd>
|
|
</dl></pre>
|
|
</div>
|
|
|
|
<h5><a name=last-of-type-pseudo>:last-of-type pseudo-class</a></h5>
|
|
|
|
<p>Same as <code>:nth-last-of-type(1)</code>. The
|
|
<code>:last-of-type</code> pseudo-class represents an element that is
|
|
the last sibling of its type in the list of children of its parent
|
|
element.</p>
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<p>The following selector represents the last data cell
|
|
<code>td</code> of a table row.</p>
|
|
<pre>tr > td:last-of-type</pre>
|
|
</div>
|
|
|
|
<h5><a name=only-child-pseudo>:only-child pseudo-class</a></h5>
|
|
|
|
<p>Represents an element that has a parent element and whose parent
|
|
element has no other element children. Same as
|
|
<code>:first-child:last-child</code> or
|
|
<code>:nth-child(1):nth-last-child(1)</code>, but with a lower
|
|
specificity.</p>
|
|
|
|
<h5><a name=only-of-type-pseudo>:only-of-type pseudo-class</a></h5>
|
|
|
|
<p>Represents an element that has a parent element and whose parent
|
|
element has no other element children with the same element name. Same
|
|
as <code>:first-of-type:last-of-type</code> or
|
|
<code>:nth-of-type(1):nth-last-of-type(1)</code>, but with a lower
|
|
specificity.</p>
|
|
|
|
|
|
<h5><a name=empty-pseudo></a>:empty pseudo-class</h5>
|
|
|
|
<p>The <code>:empty</code> pseudo-class represents an element that has
|
|
no children at all. In terms of the DOM, only element nodes and text
|
|
nodes (including CDATA nodes and entity references) whose data has a
|
|
non-zero length must be considered as affecting emptiness; comments,
|
|
PIs, and other nodes must not affect whether an element is considered
|
|
empty or not.</p>
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<p><code>p:empty</code> is a valid representation of the following fragment:</p>
|
|
<pre><p></p></pre>
|
|
<p><code>foo:empty</code> is not a valid representation for the
|
|
following fragments:</p>
|
|
<pre><foo>bar</foo></pre>
|
|
<pre><foo><bar>bla</bar></foo></pre>
|
|
<pre><foo>this is not <bar>:empty</bar></foo></pre>
|
|
</div>
|
|
|
|
<h4><a name=content-selectors>6.6.6. Blank</a></h4> <!-- It's the Return of Appendix H!!! Run away! -->
|
|
|
|
<p>This section intentionally left blank.</p>
|
|
<!-- (used to be :contains()) -->
|
|
|
|
<h4><a name=negation></a>6.6.7. The negation pseudo-class</h4>
|
|
|
|
<p>The negation pseudo-class, <code>:not(<var>X</var>)</code>, is a
|
|
functional notation taking a <a href="#simple-selectors-dfn">simple
|
|
selector</a> (excluding the negation pseudo-class itself and
|
|
pseudo-elements) as an argument. It represents an element that is not
|
|
represented by the argument.
|
|
|
|
<!-- pseudo-elements are not simple selectors, so the above paragraph
|
|
may be a bit confusing -->
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<p>The following CSS selector matches all <code>button</code>
|
|
elements in an HTML document that are not disabled.</p>
|
|
<pre>button:not([DISABLED])</pre>
|
|
<p>The following selector represents all but <code>FOO</code>
|
|
elements.</p>
|
|
<pre>*:not(FOO)</pre>
|
|
<p>The following group of selectors represents all HTML elements
|
|
except links.</p>
|
|
<pre>html|*:not(:link):not(:visited)</pre>
|
|
</div>
|
|
|
|
<p>Default namespace declarations do not affect the argument of the
|
|
negation pseudo-class unless the argument is a universal selector or a
|
|
type selector.</p>
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<p>Assuming that the default namespace is bound to
|
|
"http://example.com/", the following selector represents all
|
|
elements that are not in that namespace:</p>
|
|
<pre>*|*:not(*)</pre>
|
|
<p>The following CSS selector matches any element being hovered,
|
|
regardless of its namespace. In particular, it is not limited to
|
|
only matching elements in the default namespace that are not being
|
|
hovered, and elements not in the default namespace don't match the
|
|
rule when they <em>are</em> being hovered.</p>
|
|
<pre>*|*:not(:hover)</pre>
|
|
</div>
|
|
|
|
<p class="note"><strong>Note</strong>: the :not() pseudo allows
|
|
useless selectors to be written. For instance <code>:not(*|*)</code>,
|
|
which represents no element at all, or <code>foo:not(bar)</code>,
|
|
which is equivalent to <code>foo</code> but with a higher
|
|
specificity.</p>
|
|
|
|
<h3><a name=pseudo-elements>7. Pseudo-elements</a></h3>
|
|
|
|
<p>Pseudo-elements create abstractions about the document tree beyond
|
|
those specified by the document language. For instance, document
|
|
languages do not offer mechanisms to access the first letter or first
|
|
line of an element's content. Pseudo-elements allow designers to refer
|
|
to this otherwise inaccessible information. Pseudo-elements may also
|
|
provide designers a way to refer to content that does not exist in the
|
|
source document (e.g., the <code>::before</code> and
|
|
<code>::after</code> pseudo-elements give access to generated
|
|
content).</p>
|
|
|
|
<p>A pseudo-element is made of two colons (<code>::</code>) followed
|
|
by the name of the pseudo-element.</p>
|
|
|
|
<p>This <code>::</code> notation is introduced by the current document
|
|
in order to establish a discrimination between pseudo-classes and
|
|
pseudo-elements. For compatibility with existing style sheets, user
|
|
agents must also accept the previous one-colon notation for
|
|
pseudo-elements introduced in CSS levels 1 and 2 (namely,
|
|
<code>:first-line</code>, <code>:first-letter</code>,
|
|
<code>:before</code> and <code>:after</code>). This compatibility is
|
|
not allowed for the new pseudo-elements introduced in CSS level 3.</p>
|
|
|
|
<p>Only one pseudo-element may appear per selector, and if present it
|
|
must appear after the sequence of simple selectors that represents the
|
|
<a href="#subject">subjects</a> of the selector. <span class="note">A
|
|
future version of this specification may allow multiple
|
|
pesudo-elements per selector.</span></p>
|
|
|
|
<h4><a name=first-line>7.1. The ::first-line pseudo-element</a></h4>
|
|
|
|
<p>The <code>::first-line</code> pseudo-element describes the contents
|
|
of the first formatted line of an element.
|
|
|
|
<div class="example">
|
|
<p>CSS example:</p>
|
|
<pre>p::first-line { text-transform: uppercase }</pre>
|
|
<p>The above rule means "change the letters of the first line of every
|
|
paragraph to uppercase".</p>
|
|
</div>
|
|
|
|
<p>The selector <code>p::first-line</code> does not match any real
|
|
HTML element. It does match a pseudo-element that conforming user
|
|
agents will insert at the beginning of every paragraph.</p>
|
|
|
|
<p>Note that the length of the first line depends on a number of
|
|
factors, including the width of the page, the font size, etc. Thus,
|
|
an ordinary HTML paragraph such as:</p>
|
|
|
|
<pre>
|
|
<P>This is a somewhat long HTML
|
|
paragraph that will be broken into several
|
|
lines. The first line will be identified
|
|
by a fictional tag sequence. The other lines
|
|
will be treated as ordinary lines in the
|
|
paragraph.</P>
|
|
</pre>
|
|
|
|
<p>the lines of which happen to be broken as follows:
|
|
|
|
<pre>
|
|
THIS IS A SOMEWHAT LONG HTML PARAGRAPH THAT
|
|
will be broken into several lines. The first
|
|
line will be identified by a fictional tag
|
|
sequence. The other lines will be treated as
|
|
ordinary lines in the paragraph.
|
|
</pre>
|
|
|
|
<p>This paragraph might be "rewritten" by user agents to include the
|
|
<em>fictional tag sequence</em> for <code>::first-line</code>. This
|
|
fictional tag sequence helps to show how properties are inherited.</p>
|
|
|
|
<pre>
|
|
<P><b><P::first-line></b> This is a somewhat long HTML
|
|
paragraph that <b></P::first-line></b> will be broken into several
|
|
lines. The first line will be identified
|
|
by a fictional tag sequence. The other lines
|
|
will be treated as ordinary lines in the
|
|
paragraph.</P>
|
|
</pre>
|
|
|
|
<p>If a pseudo-element breaks up a real element, the desired effect
|
|
can often be described by a fictional tag sequence that closes and
|
|
then re-opens the element. Thus, if we mark up the previous paragraph
|
|
with a <code>span</code> element:</p>
|
|
|
|
<pre>
|
|
<P><b><SPAN class="test"></b> This is a somewhat long HTML
|
|
paragraph that will be broken into several
|
|
lines.<b></SPAN></b> The first line will be identified
|
|
by a fictional tag sequence. The other lines
|
|
will be treated as ordinary lines in the
|
|
paragraph.</P>
|
|
</pre>
|
|
|
|
<p>the user agent could simulate start and end tags for
|
|
<code>span</code> when inserting the fictional tag sequence for
|
|
<code>::first-line</code>.
|
|
|
|
<pre>
|
|
<P><P::first-line><b><SPAN class="test"></b> This is a
|
|
somewhat long HTML
|
|
paragraph that will <b></SPAN></b></P::first-line><b><SPAN class="test"></b> be
|
|
broken into several
|
|
lines.<b></SPAN></b> The first line will be identified
|
|
by a fictional tag sequence. The other lines
|
|
will be treated as ordinary lines in the
|
|
paragraph.</P>
|
|
</pre>
|
|
|
|
<p>In CSS, the <code>::first-line</code> pseudo-element can only be
|
|
attached to a block-level element, an inline-block, a table-caption,
|
|
or a table-cell.</p>
|
|
|
|
<p><a name="first-formatted-line"></a>The "first formatted line" of an
|
|
element may occur inside a
|
|
block-level descendant in the same flow (i.e., a block-level
|
|
descendant that is not positioned and not a float). E.g., the first
|
|
line of the <code>div</code> in <code><DIV><P>This
|
|
line...</P></DIV></code> is the first line of the <code>p</code> (assuming
|
|
that both <code>p</code> and <code>div</code> are block-level).
|
|
|
|
<p>The first line of a table-cell or inline-block cannot be the first
|
|
formatted line of an ancestor element. Thus, in <code><DIV><P
|
|
STYLE="display: inline-block">Hello<BR>Goodbye</P>
|
|
etcetera</DIV></code> the first formatted line of the
|
|
<code>div</code> is not the line "Hello".
|
|
|
|
<p class="note">Note that the first line of the <code>p</code> in this
|
|
fragment: <code><p><br>First...</code> doesn't contain any
|
|
letters (assuming the default style for <code>br</code> in HTML
|
|
4). The word "First" is not on the first formatted line.
|
|
|
|
<p>A UA should act as if the fictional start tags of the
|
|
<code>::first-line</code> pseudo-elements were nested just inside the
|
|
innermost enclosing block-level element. (Since CSS1 and CSS2 were
|
|
silent on this case, authors should not rely on this behavior.) Here
|
|
is an example. The fictional tag sequence for</p>
|
|
|
|
<pre>
|
|
<DIV>
|
|
<P>First paragraph</P>
|
|
<P>Second paragraph</P>
|
|
</DIV>
|
|
</pre>
|
|
|
|
<p>is</p>
|
|
|
|
<pre>
|
|
<DIV>
|
|
<P><DIV::first-line><P::first-line>First paragraph</P::first-line></DIV::first-line></P>
|
|
<P><P::first-line>Second paragraph</P::first-line></P>
|
|
</DIV>
|
|
</pre>
|
|
|
|
<p>The <code>::first-line</code> pseudo-element is similar to an
|
|
inline-level element, but with certain restrictions. In CSS, the
|
|
following properties apply to a <code>::first-line</code>
|
|
pseudo-element: font properties, color property, background
|
|
properties, 'word-spacing', 'letter-spacing', 'text-decoration',
|
|
'vertical-align', 'text-transform', 'line-height'. UAs may apply other
|
|
properties as well.</p>
|
|
|
|
|
|
<h4><a name=first-letter>7.2. The ::first-letter pseudo-element</a></h4>
|
|
|
|
<p>The <code>::first-letter</code> pseudo-element represents the first
|
|
letter of the first line of a block, if it is not preceded by any
|
|
other content (such as images or inline tables) on its line. The
|
|
::first-letter pseudo-element may be used for "initial caps" and "drop
|
|
caps", which are common typographical effects. This type of initial
|
|
letter is similar to an inline-level element if its 'float' property
|
|
is 'none'; otherwise, it is similar to a floated element.</p>
|
|
|
|
<p>In CSS, these are the properties that apply to <code>::first-letter</code>
|
|
pseudo-elements: font properties, 'text-decoration', 'text-transform',
|
|
'letter-spacing', 'word-spacing' (when appropriate), 'line-height',
|
|
'float', 'vertical-align' (only if 'float' is 'none'), margin
|
|
properties, padding properties, border properties, color property,
|
|
background properties. UAs may apply other properties as well. To
|
|
allow UAs to render a typographically correct drop cap or initial cap,
|
|
the UA may choose a line-height, width and height based on the shape
|
|
of the letter, unlike for normal elements.</p>
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<p>This example shows a possible rendering of an initial cap. Note
|
|
that the 'line-height' that is inherited by the <code>::first-letter</code>
|
|
pseudo-element is 1.1, but the UA in this example has computed the
|
|
height of the first letter differently, so that it doesn't cause any
|
|
unnecessary space between the first two lines. Also note that the
|
|
fictional start tag of the first letter is inside the <span>span</span>, and thus
|
|
the font weight of the first letter is normal, not bold as the <span>span</span>:
|
|
<pre>
|
|
p { line-height: 1.1 }
|
|
p::first-letter { font-size: 3em; font-weight: normal }
|
|
span { font-weight: bold }
|
|
...
|
|
<p><span>Het hemelsche</span> gerecht heeft zich ten lange lesten<br>
|
|
Erbarremt over my en mijn benaeuwde vesten<br>
|
|
En arme burgery, en op mijn volcx gebed<br>
|
|
En dagelix geschrey de bange stad ontzet.
|
|
</pre>
|
|
<div class="figure">
|
|
<p><img src="initial-cap.png" alt="Image illustrating the ::first-letter pseudo-element">
|
|
</div>
|
|
</div>
|
|
|
|
<div class="example">
|
|
<p>The following CSS will make a drop cap initial letter span about two lines:</p>
|
|
|
|
<pre>
|
|
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN">
|
|
<HTML>
|
|
<HEAD>
|
|
<TITLE>Drop cap initial letter</TITLE>
|
|
<STYLE type="text/css">
|
|
P { font-size: 12pt; line-height: 1.2 }
|
|
P::first-letter { font-size: 200%; font-weight: bold; float: left }
|
|
SPAN { text-transform: uppercase }
|
|
</STYLE>
|
|
</HEAD>
|
|
<BODY>
|
|
<P><SPAN>The first</SPAN> few words of an article
|
|
in The Economist.</P>
|
|
</BODY>
|
|
</HTML>
|
|
</pre>
|
|
|
|
<p>This example might be formatted as follows:</p>
|
|
|
|
<div class="figure">
|
|
<P><img src="first-letter.gif" alt="Image illustrating the combined effect of the ::first-letter and ::first-line pseudo-elements"></p>
|
|
</div>
|
|
|
|
<p>The <span class="index-inst" title="fictional tag
|
|
sequence">fictional tag sequence</span> is:</p>
|
|
|
|
<pre>
|
|
<P>
|
|
<SPAN>
|
|
<P::first-letter>
|
|
T
|
|
</P::first-letter>he first
|
|
</SPAN>
|
|
few words of an article in the Economist.
|
|
</P>
|
|
</pre>
|
|
|
|
<p>Note that the <code>::first-letter</code> pseudo-element tags abut
|
|
the content (i.e., the initial character), while the ::first-line
|
|
pseudo-element start tag is inserted right after the start tag of the
|
|
block element.</p> </div>
|
|
|
|
<p>In order to achieve traditional drop caps formatting, user agents
|
|
may approximate font sizes, for example to align baselines. Also, the
|
|
glyph outline may be taken into account when formatting.</p>
|
|
|
|
<p>Punctuation (i.e, characters defined in Unicode in the "open" (Ps),
|
|
"close" (Pe), "initial" (Pi). "final" (Pf) and "other" (Po)
|
|
punctuation classes), that precedes or follows the first letter should
|
|
be included. <a href="#refsUNICODE">[UNICODE]</a></p>
|
|
|
|
<div class="figure">
|
|
<P><img src="first-letter2.gif" alt="Quotes that precede the
|
|
first letter should be included."></p>
|
|
</div>
|
|
|
|
<p>The <code>::first-letter</code> also applies if the first letter is
|
|
in fact a digit, e.g., the "6" in "67 million dollars is a lot of
|
|
money."</p>
|
|
|
|
<p>In CSS, the <code>::first-letter</code> pseudo-element applies to
|
|
block, list-item, table-cell, table-caption, and inline-block
|
|
elements. <span class="note">A future version of this specification
|
|
may allow this pesudo-element to apply to more element
|
|
types.</span></p>
|
|
|
|
<p>The <code>::first-letter</code> pseudo-element can be used with all
|
|
such elements that contain text, or that have a descendant in the same
|
|
flow that contains text. A UA should act as if the fictional start tag
|
|
of the ::first-letter pseudo-element is just before the first text of
|
|
the element, even if that first text is in a descendant.</p>
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<p>The fictional tag sequence for this HTMLfragment:
|
|
<pre><div>
|
|
<p>The first text.</pre>
|
|
<p>is:
|
|
<pre><div>
|
|
<p><div::first-letter><p::first-letter>T</...></...>he first text.</pre>
|
|
</div>
|
|
|
|
<p>The first letter of a table-cell or inline-block cannot be the
|
|
first letter of an ancestor element. Thus, in <code><DIV><P
|
|
STYLE="display: inline-block">Hello<BR>Goodbye</P>
|
|
etcetera</DIV></code> the first letter of the <code>div</code> is not the
|
|
letter "H". In fact, the <code>div</code> doesn't have a first letter.
|
|
|
|
<p>The first letter must occur on the <a
|
|
href="#first-formatted-line">first formatted line.</a> For example, in
|
|
this fragment: <code><p><br>First...</code> the first line
|
|
doesn't contain any letters and <code>::first-letter</code> doesn't
|
|
match anything (assuming the default style for <code>br</code> in HTML
|
|
4). In particular, it does not match the "F" of "First."
|
|
|
|
<p>In CSS, if an element is a list item ('display: list-item'), the
|
|
<code>::first-letter</code> applies to the first letter in the
|
|
principal box after the marker. UAs may ignore
|
|
<code>::first-letter</code> on list items with 'list-style-position:
|
|
inside'. If an element has <code>::before</code> or
|
|
<code>::after</code> content, the <code>::first-letter</code> applies
|
|
to the first letter of the element <em>including</em> that content.
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<p>After the rule 'p::before {content: "Note: "}', the selector
|
|
'p::first-letter' matches the "N" of "Note".</p>
|
|
</div>
|
|
|
|
<p>Some languages may have specific rules about how to treat certain
|
|
letter combinations. In Dutch, for example, if the letter combination
|
|
"ij" appears at the beginning of a word, both letters should be
|
|
considered within the <code>::first-letter</code> pseudo-element.
|
|
|
|
<p>If the letters that would form the ::first-letter are not in the
|
|
same element, such as "'T" in <code><p>'<em>T...</code>, the UA
|
|
may create a ::first-letter pseudo-element from one of the elements,
|
|
both elements, or simply not create a pseudo-element.</p>
|
|
|
|
<p>Similarly, if the first letter(s) of the block are not at the start
|
|
of the line (for example due to bidirectional reordering), then the UA
|
|
need not create the pseudo-element(s).
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<p><a name="overlapping-example">The following example</a> illustrates
|
|
how overlapping pseudo-elements may interact. The first letter of
|
|
each P element will be green with a font size of '24pt'. The rest of
|
|
the first formatted line will be 'blue' while the rest of the
|
|
paragraph will be 'red'.</p>
|
|
|
|
<pre>p { color: red; font-size: 12pt }
|
|
p::first-letter { color: green; font-size: 200% }
|
|
p::first-line { color: blue }
|
|
|
|
<P>Some text that ends up on two lines</P></pre>
|
|
|
|
<p>Assuming that a line break will occur before the word "ends", the
|
|
<span class="index-inst" title="fictional tag sequence">fictional tag
|
|
sequence</span> for this fragment might be:</p>
|
|
|
|
<pre><P>
|
|
<P::first-line>
|
|
<P::first-letter>
|
|
S
|
|
</P::first-letter>ome text that
|
|
</P::first-line>
|
|
ends up on two lines
|
|
</P></pre>
|
|
|
|
<p>Note that the <code>::first-letter</code> element is inside the <code>::first-line</code>
|
|
element. Properties set on <code>::first-line</code> are inherited by
|
|
<code>::first-letter</code>, but are overridden if the same property is set on
|
|
<code>::first-letter</code>.</p>
|
|
</div>
|
|
|
|
|
|
<h4><a name=UIfragments>7.3.</a> <a name=selection>The ::selection pseudo-element</a></h4>
|
|
|
|
<p>The <code>::selection</code> pseudo-element applies to the portion
|
|
of a document that has been highlighted by the user. This also
|
|
applies, for example, to selected text within an editable text
|
|
field. This pseudo-element should not be confused with the <code><a
|
|
href="#checked">:checked</a></code> pseudo-class (which used to be
|
|
named <code>:selected</code>)
|
|
|
|
<p>Although the <code>::selection</code> pseudo-element is dynamic in
|
|
nature, and is altered by user action, it is reasonable to expect that
|
|
when a UA re-renders to a static medium (such as a printed page, see
|
|
<a href="#refsCSS21">[CSS21]</a>) which was originally rendered to a
|
|
dynamic medium (like screen), the UA may wish to transfer the current
|
|
<code>::selection</code> state to that other medium, and have all the
|
|
appropriate formatting and rendering take effect as well. This is not
|
|
required &mdart; UAs may omit the <code>::selection</code>
|
|
pseudo-element for static media.
|
|
|
|
<p>These are the CSS properties that apply to <code>::selection</code>
|
|
pseudo-elements: color, background, cursor (optional), outline
|
|
(optional). The computed value of the 'background-image' property on
|
|
<code>::selection</code> may be ignored.
|
|
|
|
|
|
<h4><a name=gen-content>7.4. The ::before and ::after pseudo-elements</a></h4>
|
|
|
|
<p>The <code>::before</code> and <code>::after</code> pseudo-elements
|
|
can be used to describe generated content before or after an element's
|
|
content. They are explained in CSS 2.1 <a
|
|
href="#refsCSS21">[CSS21]</a>.</p>
|
|
|
|
<p>When the <code>::first-letter</code> and <code>::first-line</code>
|
|
pseudo-elements are combined with <code>::before</code> and
|
|
<code>::after</code>, they apply to the first letter or line of the
|
|
element including the inserted text.</p>
|
|
|
|
<h2><a name=combinators>8. Combinators</a></h2>
|
|
|
|
<h3><a name=descendant-combinators>8.1. Descendant combinator</a></h3>
|
|
|
|
<p>At times, authors may want selectors to describe an element that is
|
|
the descendant of another element in the document tree (e.g., "an
|
|
<code>EM</code> element that is contained within an <code>H1</code>
|
|
element"). Descendant combinators express such a relationship. A
|
|
descendant combinator is <a href="#whitespace">white space</a> that
|
|
separates two sequences of simple selectors. A selector of the form
|
|
"<code>A B</code>" represents an element <code>B</code> that is an
|
|
arbitrary descendant of some ancestor element <code>A</code>.
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<p>For example, consider the following selector:</p>
|
|
<pre>h1 em</pre>
|
|
<p>It represents an <code>em</code> element being the descendant of
|
|
an <code>h1</code> element. It is a correct and valid, but partial,
|
|
description of the following fragment:</p>
|
|
<pre><h1>This <span class="myclass">headline
|
|
is <em>very</em> important</span></h1></pre>
|
|
<p>The following selector:</p>
|
|
<pre>div * p</pre>
|
|
<p>represents a <code>p</code> element that is a grandchild or later
|
|
descendant of a <code>div</code> element. Note the whitespace on
|
|
either side of the "*" is not part of the universal selector; the
|
|
whitespace is a combinator indicating that the DIV must be the
|
|
ancestor of some element, and that that element must be an ancestor
|
|
of the P.</p>
|
|
<p>The following selector, which combines descendant combinators and
|
|
<a href="#attribute-selectors">attribute selectors</a>, represents an
|
|
element that (1) has the <code>href</code> attribute set and (2) is
|
|
inside a <code>p</code> that is itself inside a <code>div</code>:</p>
|
|
<pre>div p *[href]</pre>
|
|
</div>
|
|
|
|
<h3><a name=child-combinators>8.2. Child combinators</a></h3>
|
|
|
|
<p>A <dfn>child combinator</dfn> describes a childhood relationship
|
|
between two elements. A child combinator is made of the
|
|
"greater-than sign" (<code>></code>) character and
|
|
separates two sequences of simple selectors.
|
|
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<p>The following selector represents a <code>p</code> element that is
|
|
child of <code>body</code>:</p>
|
|
<pre>body > p</pre>
|
|
<p>The following example combines descendant combinators and child
|
|
combinators.</p>
|
|
<pre>div ol>li p</pre><!-- LEAVE THOSE SPACES OUT! see below -->
|
|
<p>It represents a <code>p</code> element that is a descendant of an
|
|
<code>li</code> element; the <code>li</code> element must be the
|
|
child of an <code>ol</code> element; the <code>ol</code> element must
|
|
be a descendant of a <code>div</code>. Notice that the optional white
|
|
space around the ">" combinator has been left out.</p>
|
|
</div>
|
|
|
|
<p>For information on selecting the first child of an element, please
|
|
see the section on the <code><a
|
|
href="#structural-pseudos">:first-child</a></code> pseudo-class
|
|
above.</p>
|
|
|
|
<h3><a name=sibling-combinators>8.3. Sibling combinators</a></h3>
|
|
|
|
<p>There are two different sibling combinators: the adjacent sibling
|
|
combinator and the general sibling combinator. In both cases,
|
|
non-element nodes (e.g. text between elements) are ignored when
|
|
considering adjacency of elements.</p>
|
|
|
|
<h4><a name=adjacent-sibling-combinators>8.3.1. Adjacent sibling combinator</a></h4>
|
|
|
|
<p>The adjacent sibling combinator is made of the "plus
|
|
sign" (U+002B, <code>+</code>) character that separates two
|
|
sequences of simple selectors. The elements represented by the two
|
|
sequences share the same parent in the document tree and the element
|
|
represented by the first sequence immediately precedes the element
|
|
represented by the second one.</p>
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<p>The following selector represents a <code>p</code> element
|
|
immediately following a <code>math</code> element:</p>
|
|
<pre>math + p</pre>
|
|
<p>The following selector is conceptually similar to the one in the
|
|
previous example, except that it adds an attribute selector &mdart; it
|
|
adds a constraint to the <code>h1</code> element, that it must have
|
|
<code>class="opener"</code>:</p>
|
|
<pre>h1.opener + h2</pre>
|
|
</div>
|
|
|
|
|
|
<h4><a name=general-sibling-combinators>8.3.2. General sibling combinator</a></h4>
|
|
|
|
<p>The general sibling combinator is made of the "tilde"
|
|
(U+007E, <code>~</code>) character that separates two sequences of
|
|
simple selectors. The elements represented by the two sequences share
|
|
the same parent in the document tree and the element represented by
|
|
the first sequence precedes (not necessarily immediately) the element
|
|
represented by the second one.</p>
|
|
|
|
<div class="example">
|
|
<p>Example:</p>
|
|
<pre>h1 ~ pre</pre>
|
|
<p>represents a <code>pre</code> element following an <code>h1</code>. It
|
|
is a correct and valid, but partial, description of:</p>
|
|
<pre><h1>Definition of the function a</h1>
|
|
<p>Function a(x) has to be applied to all figures in the table.</p>
|
|
<pre>function a(x) = 12x/13.5</pre></pre>
|
|
</div>
|
|
|
|
<h2><a name=specificity>9. Calculating a selector's specificity</a></h2>
|
|
|
|
<p>A selector's specificity is calculated as follows:</p>
|
|
|
|
<ul>
|
|
<li>count the number of ID selectors in the selector (= a)</li>
|
|
<li>count the number of class selectors, attributes selectors, and pseudo-classes in the selector (= b)</li>
|
|
<li>count the number of element names in the selector (= c)</li>
|
|
<li>ignore pseudo-elements</li>
|
|
</ul>
|
|
|
|
<p>Selectors inside <a href="#negation">the negation pseudo-class</a>
|
|
are counted like any other, but the negation itself does not count as
|
|
a pseudo-class.</p>
|
|
|
|
<p>Concatenating the three numbers a-b-c (in a number system with a
|
|
large base) gives the specificity.</p>
|
|
|
|
<div class="example">
|
|
<p>Examples:</p>
|
|
<pre>* /* a=0 b=0 c=0 -> specificity = 0 */
|
|
LI /* a=0 b=0 c=1 -> specificity = 1 */
|
|
UL LI /* a=0 b=0 c=2 -> specificity = 2 */
|
|
UL OL+LI /* a=0 b=0 c=3 -> specificity = 3 */
|
|
H1 + *[REL=up] /* a=0 b=1 c=1 -> specificity = 11 */
|
|
UL OL LI.red /* a=0 b=1 c=3 -> specificity = 13 */
|
|
LI.red.level /* a=0 b=2 c=1 -> specificity = 21 */
|
|
#x34y /* a=1 b=0 c=0 -> specificity = 100 */
|
|
#s12:not(FOO) /* a=1 b=0 c=1 -> specificity = 101 */
|
|
</pre>
|
|
</div>
|
|
|
|
<p class="note"><strong>Note:</strong> the specificity of the styles
|
|
specified in an HTML <code>style</code> attribute is described in CSS
|
|
2.1. <a href="#refsCSS21">[CSS21]</a>.</p>
|
|
|
|
<h2><a name=w3cselgrammar>10. The grammar of Selectors</a></h2>
|
|
|
|
<h3><a name=grammar>10.1. Grammar</a></h3>
|
|
|
|
<p>The grammar below defines the syntax of Selectors. It is globally
|
|
LL(1) and can be locally LL(2) (but note that most UA's should not use
|
|
it directly, since it doesn't express the parsing conventions). The
|
|
format of the productions is optimized for human consumption and some
|
|
shorthand notations beyond Yacc (see <a href="#refsYACC">[YACC]</a>)
|
|
are used:</p>
|
|
|
|
<ul>
|
|
<li><b>*</b>: 0 or more
|
|
<li><b>+</b>: 1 or more
|
|
<li><b>?</b>: 0 or 1
|
|
<li><b>|</b>: separates alternatives
|
|
<li><b>[ ]</b>: grouping </li>
|
|
</ul>
|
|
|
|
<p>The productions are:</p>
|
|
|
|
<pre>selectors_group
|
|
: selector [ COMMA S* selector ]*
|
|
;
|
|
|
|
selector
|
|
: simple_selector_sequence [ combinator simple_selector_sequence ]*
|
|
;
|
|
|
|
combinator
|
|
/* combinators can be surrounded by white space */
|
|
: PLUS S* | GREATER S* | TILDE S* | S+
|
|
;
|
|
|
|
simple_selector_sequence
|
|
: [ type_selector | universal ]
|
|
[ HASH | class | attrib | pseudo | negation ]*
|
|
| [ HASH | class | attrib | pseudo | negation ]+
|
|
;
|
|
|
|
type_selector
|
|
: [ namespace_prefix ]? element_name
|
|
;
|
|
|
|
namespace_prefix
|
|
: [ IDENT | '*' ]? '|'
|
|
;
|
|
|
|
element_name
|
|
: IDENT
|
|
;
|
|
|
|
universal
|
|
: [ namespace_prefix ]? '*'
|
|
;
|
|
|
|
class
|
|
: '.' IDENT
|
|
;
|
|
|
|
attrib
|
|
: '[' S* [ namespace_prefix ]? IDENT S*
|
|
[ [ PREFIXMATCH |
|
|
SUFFIXMATCH |
|
|
SUBSTRINGMATCH |
|
|
'=' |
|
|
INCLUDES |
|
|
DARTMATCH ] S* [ IDENT | STRING ] S*
|
|
]? ']'
|
|
;
|
|
|
|
pseudo
|
|
/* '::' starts a pseudo-element, ':' a pseudo-class */
|
|
/* Exceptions: :first-line, :first-letter, :before and :after. */
|
|
/* Note that pseudo-elements are restricted to one per selector and */
|
|
/* occur only in the last simple_selector_sequence. */
|
|
: ':' ':'? [ IDENT | functional_pseudo ]
|
|
;
|
|
|
|
functional_pseudo
|
|
: FUNCTION S* expression ')'
|
|
;
|
|
|
|
expression
|
|
/* In CSS3, the expressions are identifiers, strings, */
|
|
/* or of the form "an+b" */
|
|
: [ [ PLUS | '-' | DIMENSION | NUMBER | STRING | IDENT ] S* ]+
|
|
;
|
|
|
|
negation
|
|
: NOT S* negation_arg S* ')'
|
|
;
|
|
|
|
negation_arg
|
|
: type_selector | universal | HASH | class | attrib | pseudo
|
|
;</pre>
|
|
|
|
|
|
<h3><a name=lex>10.2. Lexical scanner</a></h3>
|
|
|
|
<p>The following is the <a name=x3>tokenizer</a>, written in Flex (see
|
|
<a href="#refsFLEX">[FLEX]</a>) notation. The tokenizer is
|
|
case-insensitive.</p>
|
|
|
|
<p>The two occurrences of "\377" represent the highest character
|
|
number that current versions of Flex can deal with (decimal 255). They
|
|
should be read as "\4177777" (decimal 1114111), which is the highest
|
|
possible code point in Unicode/ISO-10646. <a
|
|
href="#refsUNICODE">[UNICODE]</a></p>
|
|
|
|
<pre>%option case-insensitive
|
|
|
|
ident [-]?{nmstart}{nmchar}*
|
|
name {nmchar}+
|
|
nmstart [_a-z]|{nonascii}|{escape}
|
|
nonascii [^\0-\177]
|
|
unicode \\[0-9a-f]{1,6}(\r\n|[ \n\r\t\f])?
|
|
escape {unicode}|\\[^\n\r\f0-9a-f]
|
|
nmchar [_a-z0-9-]|{nonascii}|{escape}
|
|
num [0-9]+|[0-9]*\.[0-9]+
|
|
string {string1}|{string2}
|
|
string1 \"([^\n\r\f\\"]|\\{nl}|{nonascii}|{escape})*\"
|
|
string2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*\'
|
|
invalid {invalid1}|{invalid2}
|
|
invalid1 \"([^\n\r\f\\"]|\\{nl}|{nonascii}|{escape})*
|
|
invalid2 \'([^\n\r\f\\']|\\{nl}|{nonascii}|{escape})*
|
|
nl \n|\r\n|\r|\f
|
|
w [ \t\r\n\f]*
|
|
|
|
%%
|
|
|
|
[ \t\r\n\f]+ return S;
|
|
|
|
"~=" return INCLUDES;
|
|
"|=" return DARTMATCH;
|
|
"^=" return PREFIXMATCH;
|
|
"$=" return SUFFIXMATCH;
|
|
"*=" return SUBSTRINGMATCH;
|
|
{ident} return IDENT;
|
|
{string} return STRING;
|
|
{ident}"(" return FUNCTION;
|
|
{num} return NUMBER;
|
|
"#"{name} return HASH;
|
|
{w}"+" return PLUS;
|
|
{w}">" return GREATER;
|
|
{w}"," return COMMA;
|
|
{w}"~" return TILDE;
|
|
":not(" return NOT;
|
|
@{ident} return ATKEYWORD;
|
|
{invalid} return INVALID;
|
|
{num}% return PERCENTAGE;
|
|
{num}{ident} return DIMENSION;
|
|
"<!--" return CDO;
|
|
"-->" return CDC;
|
|
|
|
"url("{w}{string}{w}")" return URI;
|
|
"url("{w}([!#$%&*-~]|{nonascii}|{escape})*{w}")" return URI;
|
|
U\+[0-9a-f?]{1,6}(-[0-9a-f]{1,6})? return UNICODE_RANGE;
|
|
|
|
\/\*[^*]*\*+([^/*][^*]*\*+)*\/ /* ignore comments */
|
|
|
|
. return *yytext;</pre>
|
|
|
|
|
|
|
|
<h2><a name=downlevel>11. Namespaces and down-level clients</a></h2>
|
|
|
|
<p>An important issue is the interaction of CSS selectors with XML
|
|
documents in web clients that were produced prior to this
|
|
document. Unfortunately, due to the fact that namespaces must be
|
|
matched based on the URI which identifies the namespace, not the
|
|
namespace prefix, some mechanism is required to identify namespaces in
|
|
CSS by their URI as well. Without such a mechanism, it is impossible
|
|
to construct a CSS style sheet which will properly match selectors in
|
|
all cases against a random set of XML documents. However, given
|
|
complete knowledge of the XML document to which a style sheet is to be
|
|
applied, and a limited use of namespaces within the XML document, it
|
|
is possible to construct a style sheet in which selectors would match
|
|
elements and attributes correctly.</p>
|
|
|
|
<p>It should be noted that a down-level CSS client will (if it
|
|
properly conforms to CSS forward compatible parsing rules) ignore all
|
|
<code>@namespace</code> at-rules, as well as all style rules that make
|
|
use of namespace qualified element type or attribute selectors. The
|
|
syntax of delimiting namespace prefixes in CSS was deliberately chosen
|
|
so that down-level CSS clients would ignore the style rules rather
|
|
than possibly match them incorrectly.</p>
|
|
|
|
<p>The use of default namespaces in CSS makes it possible to write
|
|
element type selectors that will function in both namespace aware CSS
|
|
clients as well as down-level clients. It should be noted that
|
|
down-level clients may incorrectly match selectors against XML
|
|
elements in other namespaces.</p>
|
|
|
|
<p>The following are scenarios and examples in which it is possible to
|
|
construct style sheets which would function properly in web clients
|
|
that do not implement this proposal.</p>
|
|
|
|
<ol>
|
|
<li>
|
|
|
|
<p>The XML document does not use namespaces.</p>
|
|
|
|
<ul>
|
|
|
|
<li>In this case, it is obviously not necessary to declare or use
|
|
namespaces in the style sheet. Standard CSS element type and
|
|
attribute selectors will function adequately in a down-level
|
|
client.</li>
|
|
|
|
<li>In a CSS namespace aware client, the default behavior of
|
|
element selectors matching without regard to namespace will
|
|
function properly against all elements, since no namespaces are
|
|
present. However, the use of specific element type selectors that
|
|
match only elements that have no namespace ("<code>|name</code>")
|
|
will guarantee that selectors will match only XML elements that do
|
|
not have a declared namespace. </li>
|
|
|
|
</ul>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
|
|
<p>The XML document defines a single, default namespace used
|
|
throughout the document. No namespace prefixes are used in element
|
|
names.</p>
|
|
|
|
<ul>
|
|
|
|
<li>In this case, a down-level client will function as if
|
|
namespaces were not used in the XML document at all. Standard CSS
|
|
element type and attribute selectors will match against all
|
|
elements. </li>
|
|
|
|
</ul>
|
|
|
|
</li>
|
|
|
|
<li>
|
|
|
|
<p>The XML document does <b>not</b> use a default namespace, all
|
|
namespace prefixes used are known to the style sheet author, and
|
|
there is a direct mapping between namespace prefixes and namespace
|
|
URIs. (A given prefix may only be mapped to one namespace URI
|
|
throughout the XML document; there may be multiple prefixes mapped
|
|
to the same URI).</p>
|
|
|
|
<ul>
|
|
|
|
<li>In this case, the down-level client will view and match
|
|
element type and attribute selectors based on their fully
|
|
qualified name, not the local part as outlined in the <a
|
|
href="#typenmsp">Type selectors and Namespaces</a> section. CSS
|
|
selectors may be declared using an escaped colon "<code>\:</code>"
|
|
to describe the fully qualified names, e.g.
|
|
"<code>html\:h1</code>" will match
|
|
<code><html:h1></code>. Selectors using the qualified name
|
|
will only match XML elements that use the same prefix. Other
|
|
namespace prefixes used in the XML that are mapped to the same URI
|
|
will not match as expected unless additional CSS style rules are
|
|
declared for them.</li>
|
|
|
|
<li>Note that selectors declared in this fashion will
|
|
<em>only</em> match in down-level clients. A CSS namespace aware
|
|
client will match element type and attribute selectors based on
|
|
the name's local part. Selectors declared with the fully
|
|
qualified name will not match (unless there is no namespace prefix
|
|
in the fully qualified name).</li>
|
|
|
|
</ul>
|
|
|
|
</li>
|
|
|
|
</ol>
|
|
|
|
<p>In other scenarios: when the namespace prefixes used in the XML are
|
|
not known in advance by the style sheet author; or a combination of
|
|
elements with no namespace are used in conjunction with elements using
|
|
a default namespace; or the same namespace prefix is mapped to
|
|
<em>different</em> namespace URIs within the same document, or in
|
|
different documents; it is impossible to construct a CSS style sheet
|
|
that will function properly against all elements in those documents,
|
|
unless, the style sheet is written using a namespace URI syntax (as
|
|
outlined in this document or similar) and the document is processed by
|
|
a CSS and XML namespace aware client.</p>
|
|
|
|
<h2><a name=profiling>12. Profiles</a></h2>
|
|
|
|
<p>Each specification using Selectors must define the subset of W3C
|
|
Selectors it allows and excludes, and describe the local meaning of
|
|
all the components of that subset.</p>
|
|
|
|
<p>Non normative examples:
|
|
|
|
<div class="profile">
|
|
<table class="tprofile">
|
|
<tbody>
|
|
<tr>
|
|
<th class="title" colspan=2>Selectors profile</th></tr>
|
|
<tr>
|
|
<th>Specification</th>
|
|
<td>CSS level 1</td></tr>
|
|
<tr>
|
|
<th>Accepts</th>
|
|
<td>type selectors<br>class selectors<br>ID selectors<br>:link,
|
|
:visited and :active pseudo-classes<br>descendant combinator
|
|
<br>::first-line and ::first-letter pseudo-elements</td></tr>
|
|
<tr>
|
|
<th>Excludes</th>
|
|
<td>
|
|
|
|
<p>universal selector<br>attribute selectors<br>:hover and :focus
|
|
pseudo-classes<br>:target pseudo-class<br>:lang() pseudo-class<br>all UI
|
|
element states pseudo-classes<br>all structural
|
|
pseudo-classes<br>negation pseudo-class<br>all
|
|
UI element fragments pseudo-elements<br>::before and ::after
|
|
pseudo-elements<br>child combinators<br>sibling combinators
|
|
|
|
<p>namespaces</td></tr>
|
|
<tr>
|
|
<th>Extra constraints</th>
|
|
<td>only one class selector allowed per sequence of simple
|
|
selectors</td></tr></tbody></table><br><br>
|
|
<table class="tprofile">
|
|
<tbody>
|
|
<tr>
|
|
<th class="title" colspan=2>Selectors profile</th></tr>
|
|
<tr>
|
|
<th>Specification</th>
|
|
<td>CSS level 2</td></tr>
|
|
<tr>
|
|
<th>Accepts</th>
|
|
<td>type selectors<br>universal selector<br>attribute presence and
|
|
values selectors<br>class selectors<br>ID selectors<br>:link, :visited,
|
|
:active, :hover, :focus, :lang() and :first-child pseudo-classes
|
|
<br>descendant combinator<br>child combinator<br>adjacent sibling
|
|
combinator<br>::first-line and ::first-letter pseudo-elements<br>::before
|
|
and ::after pseudo-elements</td></tr>
|
|
<tr>
|
|
<th>Excludes</th>
|
|
<td>
|
|
|
|
<p>content selectors<br>substring matching attribute
|
|
selectors<br>:target pseudo-classes<br>all UI element
|
|
states pseudo-classes<br>all structural pseudo-classes other
|
|
than :first-child<br>negation pseudo-class<br>all UI element
|
|
fragments pseudo-elements<br>general sibling combinators
|
|
|
|
<p>namespaces</td></tr>
|
|
<tr>
|
|
<th>Extra constraints</th>
|
|
<td>more than one class selector per sequence of simple selectors (CSS1
|
|
constraint) allowed</td></tr></tbody></table>
|
|
|
|
<p>In CSS, selectors express pattern matching rules that determine which style
|
|
rules apply to elements in the document tree.
|
|
|
|
<p>The following selector (CSS level 2) will <b>match</b> all anchors <code>a</code>
|
|
with attribute <code>name</code> set inside a section 1 header <code>h1</code>:
|
|
<pre>h1 a[name]</pre>
|
|
|
|
<p>All CSS declarations attached to such a selector are applied to elements
|
|
matching it. </div>
|
|
|
|
<div class="profile">
|
|
<table class="tprofile">
|
|
<tbody>
|
|
<tr>
|
|
<th class="title" colspan=2>Selectors profile</th></tr>
|
|
<tr>
|
|
<th>Specification</th>
|
|
<td>STTS 3</td>
|
|
</tr>
|
|
<tr>
|
|
<th>Accepts</th>
|
|
<td>
|
|
|
|
<p>type selectors<br>universal selectors<br>attribute selectors<br>class
|
|
selectors<br>ID selectors<br>all structural pseudo-classes<br>
|
|
all combinators
|
|
|
|
<p>namespaces</td></tr>
|
|
<tr>
|
|
<th>Excludes</th>
|
|
<td>non-accepted pseudo-classes<br>pseudo-elements<br></td></tr>
|
|
<tr>
|
|
<th>Extra constraints</th>
|
|
<td>some selectors and combinators are not allowed in fragment
|
|
descriptions on the right side of STTS declarations.</td></tr></tbody></table>
|
|
<form>
|
|
<input type="text" name="test1"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
<input type="text" name="foo"/>
|
|
</form>
|
|
|
|
<p>Selectors can be used in STTS 3 in two different
|
|
manners:
|
|
<ol>
|
|
<li>a selection mechanism equivalent to CSS selection mechanism: declarations
|
|
attached to a given selector are applied to elements matching that selector,
|
|
<li>fragment descriptions that appear on the right side of declarations.
|
|
</li></ol></div>
|
|
|
|
<h2><a name=Conformance></a>13. Conformance and requirements</h2>
|
|
|
|
<p>This section defines conformance with the present specification only.
|
|
|
|
<p>The inability of a user agent to implement part of this specification due to
|
|
the limitations of a particular device (e.g., non interactive user agents will
|
|
probably not implement dynamic pseudo-classes because they make no sense without
|
|
interactivity) does not imply non-conformance.
|
|
|
|
<p>All specifications reusing Selectors must contain a <a
|
|
href="#profiling">Profile</a> listing the
|
|
subset of Selectors it accepts or excludes, and describing the constraints
|
|
it adds to the current specification.
|
|
|
|
<p>Invalidity is caused by a parsing error, e.g. an unrecognized token or a token
|
|
which is not allowed at the current parsing point.
|
|
|
|
<p>User agents must observe the rules for handling parsing errors:
|
|
<ul>
|
|
<li>a simple selector containing an undeclared namespace prefix is invalid</li>
|
|
<li>a selector containing an invalid simple selector, an invalid combinator
|
|
or an invalid token is invalid. </li>
|
|
<li>a group of selectors containing an invalid selector is invalid.</li>
|
|
</ul>
|
|
|
|
<p class="foo test1 bar">Specifications reusing Selectors must define how to handle parsing
|
|
errors. (In the case of CSS, the entire rule in which the selector is
|
|
used is dropped.)</p>
|
|
|
|
<!-- Apparently all these references are out of date:
|
|
<p>Implementations of this specification must behave as
|
|
"recipients of text data" as defined by <a href="#refsCWWW">[CWWW]</a>
|
|
when parsing selectors and attempting matches. (In particular,
|
|
implementations must assume the data is normalized and must not
|
|
normalize it.) Normative rules for matching strings are defined in
|
|
<a href="#refsCWWW">[CWWW]</a> and <a
|
|
href="#refsUNICODE">[UNICODE]</a> and apply to implementations of this
|
|
specification.</p>-->
|
|
|
|
<h2><a name=Tests></a>14. Tests</h2>
|
|
|
|
<p>This specification has <a
|
|
href="http://www.w3.org/Style/CSS/Test/CSS3/Selectors/current/">a test
|
|
suite</a> allowing user agents to verify their basic conformance to
|
|
the specification. This test suite does not pretend to be exhaustive
|
|
and does not cover all possible combined cases of Selectors.</p>
|
|
|
|
<h2><a name=ACKS></a>15. Acknowledgements</h2>
|
|
|
|
<p>The CSS working group would like to thank everyone who has sent
|
|
comments on this specification over the years.</p>
|
|
|
|
<p>The working group would like to extend special thanks to Donna
|
|
McManus, Justin Baker, Joel Sklar, and Molly Ives Brower who perfermed
|
|
the final editorial review.</p>
|
|
|
|
<h2><a name=references>16. References</a></h2>
|
|
|
|
<dl class="refs">
|
|
|
|
<dt>[CSS1]
|
|
<dd><a name=refsCSS1></a> Bert Bos, Håkon Wium Lie; "<cite>Cascading Style Sheets, level 1</cite>", W3C Recommendation, 17 Dec 1996, revised 11 Jan 1999
|
|
<dd>(<code><a href="http://www.w3.org/TR/REC-CSS1">http://www.w3.org/TR/REC-CSS1</a></code>)
|
|
|
|
<dt>[CSS21]
|
|
<dd><a name=refsCSS21></a> Bert Bos, Tantek Çelik, Ian Hickson, Håkon Wium Lie, editors; "<cite>Cascading Style Sheets, level 2 revision 1</cite>", W3C Working Draft, 13 June 2005
|
|
<dd>(<code><a href="http://www.w3.org/TR/CSS21">http://www.w3.org/TR/CSS21</a></code>)
|
|
|
|
<dt>[CWWW]
|
|
<dd><a name=refsCWWW></a> Martin J. Dürst, François Yergeau, Misha Wolf, Asmus Freytag, Tex Texin, editors; "<cite>Character Model for the World Wide Web</cite>", W3C Recommendation, 15 February 2005
|
|
<dd>(<code><a href="http://www.w3.org/TR/charmod/">http://www.w3.org/TR/charmod/</a></code>)
|
|
|
|
<dt>[FLEX]
|
|
<dd><a name="refsFLEX"></a> "<cite>Flex: The Lexical Scanner Generator</cite>", Version 2.3.7, ISBN 1882114213
|
|
|
|
<dt>[HTML4]
|
|
<dd><a name="refsHTML4"></a> Dave Ragget, Arnaud Le Hors, Ian Jacobs, editors; "<cite>HTML 4.01 Specification</cite>", W3C Recommendation, 24 December 1999
|
|
<dd>(<a href="http://www.w3.org/TR/html4/"><code>http://www.w3.org/TR/html4/</code></a>)
|
|
|
|
<dt>[MATH]
|
|
<dd><a name="refsMATH"></a> Patrick Ion, Robert Miner, editors; "<cite>Mathematical Markup Language (MathML) 1.01</cite>", W3C Recommendation, revision of 7 July 1999
|
|
<dd>(<code><a href="http://www.w3.org/TR/REC-MathML/">http://www.w3.org/TR/REC-MathML/</a></code>)
|
|
|
|
<dt>[RFC3066]
|
|
<dd><a name="refsRFC3066"></a> H. Alvestrand; "<cite>Tags for the Identification of Languages</cite>", Request for Comments 3066, January 2001
|
|
<dd>(<a href="http://www.ietf.org/rfc/rfc3066.txt"><code>http://www.ietf.org/rfc/rfc3066.txt</code></a>)
|
|
|
|
<dt>[STTS]
|
|
<dd><a name=refsSTTS></a> Daniel Glazman; "<cite>Simple Tree Transformation Sheets 3</cite>", Electricité de France, submission to the W3C, 11 November 1998
|
|
<dd>(<code><a href="http://www.w3.org/TR/NOTE-STTS3">http://www.w3.org/TR/NOTE-STTS3</a></code>)
|
|
|
|
<dt>[SVG]
|
|
<dd><a name="refsSVG"></a> Jon Ferraiolo, 藤沢 淳, Dean Jackson, editors; "<cite>Scalable Vector Graphics (SVG) 1.1 Specification</cite>", W3C Recommendation, 14 January 2003
|
|
<dd>(<code><a href="http://www.w3.org/TR/SVG/">http://www.w3.org/TR/SVG/</a></code>)
|
|
|
|
<dt>[UNICODE]</dt>
|
|
<dd><a name="refsUNICODE"></a> <cite><a
|
|
href="http://www.unicode.org/versions/Unicode4.1.0/">The Unicode Standard, Version 4.1</a></cite>, The Unicode Consortium. Boston, MA, Addison-Wesley, March 2005. ISBN 0-321-18578-1, as amended by <a href="http://www.unicode.org/versions/Unicode4.0.1/">Unicode 4.0.1</a> and <a href="http://www.unicode.org/versions/Unicode4.1.0/">Unicode 4.1.0</a>.
|
|
<dd>(<code><a href="http://www.unicode.org/versions/">http://www.unicode.org/versions/</a></code>)</dd>
|
|
|
|
<dt>[XML10]
|
|
<dd><a name="refsXML10"></a> Tim Bray, Jean Paoli, C. M. Sperberg-McQueen, Eve Maler, François Yergeau, editors; "<cite>Extensible Markup Language (XML) 1.0 (Third Edition)</cite>", W3C Recommendation, 4 February 2004
|
|
<dd>(<a href="http://www.w3.org/TR/REC-xml/"><code>http://www.w3.org/TR/REC-xml/</code></a>)
|
|
|
|
<dt>[XMLNAMES]
|
|
<dd><a name="refsXMLNAMES"></a> Tim Bray, Dave Hollander, Andrew Layman, editors; "<cite>Namespaces in XML</cite>", W3C Recommendation, 14 January 1999
|
|
<dd>(<a href="http://www.w3.org/TR/REC-xml-names/"><code>http://www.w3.org/TR/REC-xml-names/</code></a>)
|
|
|
|
<dt>[YACC]
|
|
<dd><a name="refsYACC"></a> S. C. Johnson; "<cite>YACC &mdart; Yet another compiler compiler</cite>", Technical Report, Murray Hill, 1975
|
|
|
|
</dl>
|
|
</body>
|
|
</html>
|