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<!doctype html><html lang="en">
<head>
<meta content="text/html; charset=utf-8" http-equiv="Content-Type">
<title>CSS Backgrounds and Borders Module Level 3</title>
<meta content="width=device-width, initial-scale=1, shrink-to-fit=no" name="viewport">
<meta content="testing" name="csswg-work-status">
<meta content="CR" name="w3c-status">
<meta content="This draft contains the features of CSS relating to borders and backgrounds. The main extensions compared to <a href="https://www.w3.org/TR/CSS2/">level&nbsp;2</a> are borders consisting of images, boxes with multiple backgrounds, boxes with rounded corners and boxes with shadows." name="abstract">
<link href="../default.css" rel="stylesheet" type="text/css">
<link href="../csslogo.ico" rel="shortcut icon" type="image/x-icon">
<link href="https://www.w3.org/StyleSheets/TR/2016/W3C-CR" rel="stylesheet" type="text/css">
<meta content="Bikeshed version 1760a0346ebf3096d8d47b818b15ffcad41e99a0" name="generator">
<link href="https://www.w3.org/TR/css-backgrounds-3/" rel="canonical">
<meta content="338e47275804c1554633c27ff761cbc8158f0e09" name="document-revision">
<script defer="" src="https://test.csswg.org/harness/annotate.js#!css-backgrounds-3_dev/css-backgrounds-3" type="text/javascript"></script>
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z-index: 35;
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max-height: 500px;
overflow: auto;
padding: 0.5em 0.75em;
font: small Helvetica Neue, sans-serif, Droid Sans Fallback;
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color: black;
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display: inline-block;
position: fixed;
left: .5em;
bottom: 2em;
margin: 0 auto;
max-width: calc(100vw - 1.5em - .4em - .5em);
max-height: 30vh;
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.heading, .issue, .note, .example, li, dt {
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a.self-link {
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<body class="h-entry">
<div class="head">
<p data-fill-with="logo"><a class="logo" href="https://www.w3.org/"> <img alt="W3C" height="48" src="https://www.w3.org/StyleSheets/TR/2016/logos/W3C" width="72"> </a> </p>
<h1 class="p-name no-ref" id="title">CSS Backgrounds and Borders Module Level 3</h1>
<h2 class="no-num no-toc no-ref heading settled" id="subtitle"><span class="content">W3C Candidate Recommendation, <time class="dt-updated" datetime="2017-10-17">17 October 2017</time></span></h2>
<div data-fill-with="spec-metadata">
<dl>
<dt>This version:
<dd><a class="u-url" href="https://www.w3.org/TR/2017/CR-css-backgrounds-3-20171017/">https://www.w3.org/TR/2017/CR-css-backgrounds-3-20171017/</a>
<dt>Latest published version:
<dd><a href="https://www.w3.org/TR/css-backgrounds-3/">https://www.w3.org/TR/css-backgrounds-3/</a>
<dt>Editor's Draft:
<dd><a href="https://drafts.csswg.org/css-backgrounds/">https://drafts.csswg.org/css-backgrounds/</a>
<dt>Previous Versions:
<dd><a href="https://www.w3.org/TR/2017/CR-css-backgrounds-3-20171017/" rel="prev">https://www.w3.org/TR/2017/CR-css-backgrounds-3-20171017/</a>
<dd><a href="https://www.w3.org/TR/2014/CR-css3-background-20140909/" rel="prev">https://www.w3.org/TR/2014/CR-css3-background-20140909/</a>
<dt>Test Suite:
<dd><a href="http://test.csswg.org/suites/css3-background/nightly-unstable/">http://test.csswg.org/suites/css3-background/nightly-unstable/</a>
<dt class="editor">Editors:
<dd class="editor p-author h-card vcard" data-editor-id="3343"><a class="p-name fn u-email email" href="mailto:bert@w3.org">Bert Bos</a> (<span class="p-org org">W3C</span>)
<dd class="editor p-author h-card vcard" data-editor-id="35400"><a class="p-name fn u-url url" href="http://fantasai.inkedblade.net/contact">Elika J. Etemad / fantasai</a> (<span class="p-org org">Invited Expert</span>)
<dd class="editor p-author h-card vcard" data-editor-id="43245"><a class="p-name fn u-email email" href="mailto:brad.kemper@gmail.com">Brad Kemper</a> (<span class="p-org org">Invited Expert</span>)
<dt>Issue Tracking:
<dd><a href="https://github.com/w3c/csswg-drafts/labels/css-backgrounds-3">GitHub Issues</a>
</dl>
</div>
<div data-fill-with="warning"></div>
<p class="copyright" data-fill-with="copyright"><a href="http://www.w3.org/Consortium/Legal/ipr-notice#Copyright">Copyright</a> © 2017 <a href="http://www.w3.org/"><abbr title="World Wide Web Consortium">W3C</abbr></a><sup>®</sup> (<a href="http://www.csail.mit.edu/"><abbr title="Massachusetts Institute of Technology">MIT</abbr></a>, <a href="http://www.ercim.eu/"><abbr title="European Research Consortium for Informatics and Mathematics">ERCIM</abbr></a>, <a href="http://www.keio.ac.jp/">Keio</a>, <a href="http://ev.buaa.edu.cn/">Beihang</a>). W3C <a href="http://www.w3.org/Consortium/Legal/ipr-notice#Legal_Disclaimer">liability</a>, <a href="http://www.w3.org/Consortium/Legal/ipr-notice#W3C_Trademarks">trademark</a> and <a href="http://www.w3.org/Consortium/Legal/2015/copyright-software-and-document">permissive document license</a> rules apply. </p>
<hr title="Separator for header">
</div>
<div class="p-summary" data-fill-with="abstract">
<h2 class="no-num no-toc no-ref heading settled" id="abstract"><span class="content">Abstract</span></h2>
<p>This draft contains the features of CSS relating to borders and backgrounds. The main extensions compared to <a href="https://www.w3.org/TR/CSS2/">level 2</a> are borders consisting of images, boxes with multiple backgrounds, boxes with rounded corners and boxes with shadows.</p>
<a href="http://www.w3.org/TR/CSS/">CSS</a> is a language for describing the rendering of structured documents
(such as HTML and XML)
on screen, on paper, in speech, etc.
</div>
<h2 class="no-num no-toc no-ref heading settled" id="status"><span class="content">Status of this document</span></h2>
<div data-fill-with="status">
<p> <em>This section describes the status of this document at the time of its publication.
Other documents may supersede this document.
A list of current W3C publications and the latest revision of this technical report
can be found in the <a href="https://www.w3.org/TR/">W3C technical reports index at https://www.w3.org/TR/.</a></em> </p>
<p> This document was produced by the <a href="https://www.w3.org/Style/CSS/members">CSS Working Group</a> as a Candidate Recommendation. This document is intended to become a W3C Recommendation.
This document will remain a Candidate Recommendation at least until <time class="status-deadline" datetime="2017-11-30">30 November 2017</time> in order
to ensure the opportunity for wide review. </p>
<p> <a href="https://github.com/w3c/csswg-drafts/issues">GitHub Issues</a> are preferred for discussion of this specification.
When filing an issue, please put the text “css-backgrounds” in the title,
preferably like this:
“[css-backgrounds] <i data-lt="…summary of comment…">…summary of comment…</i>”.
All issues and comments are <a href="https://lists.w3.org/Archives/Public/public-css-archive/">archived</a>,
and there is also a <a href="https://lists.w3.org/Archives/Public/www-style/">historical archive</a>. </p>
<p> Publication as a Candidate Recommendation does not imply endorsement by the W3C
Membership. This is a draft document and may be updated, replaced or
obsoleted by other documents at any time. It is inappropriate to cite this
document as other than work in progress. </p>
<p> This document was produced by a group operating under
the <a href="https://www.w3.org/Consortium/Patent-Policy/">W3C Patent Policy</a>.
W3C maintains a <a href="https://www.w3.org/2004/01/pp-impl/32061/status" rel="disclosure">public list of any patent disclosures</a> made in connection with the deliverables of the group;
that page also includes instructions for disclosing a patent.
An individual who has actual knowledge of a patent which the individual believes contains <a href="https://www.w3.org/Consortium/Patent-Policy/#def-essential">Essential Claim(s)</a> must disclose the information in accordance with <a href="https://www.w3.org/Consortium/Patent-Policy/#sec-Disclosure">section 6 of the W3C Patent Policy</a>. </p>
<p> This document is governed by the <a href="https://www.w3.org/2017/Process-20170301/" id="w3c_process_revision">1 March 2017 W3C Process Document</a>. </p>
<p> For changes since the last draft,
see the <a href="#changes">Changes</a> section. </p>
<p></p>
</div>
<div data-fill-with="at-risk">
<p>The following features are at-risk, and may be dropped during the CR period: </p>
<ul>
<li>animatability of <a class="property" data-link-type="propdesc" href="#propdef-box-shadow" id="ref-for-propdef-box-shadow">box-shadow</a>
</ul>
<p>“At-risk” is a W3C Process term-of-art, and does not necessarily imply that the feature is in danger of being dropped or delayed. It means that the WG believes the feature may have difficulty being interoperably implemented in a timely manner, and marking it as such allows the WG to drop the feature if necessary when transitioning to the Proposed Rec stage, without having to publish a new Candidate Rec without the feature first.</p>
</div>
<nav data-fill-with="table-of-contents" id="toc">
<h2 class="no-num no-toc no-ref" id="contents">Table of Contents</h2>
<ol class="toc" role="directory">
<li><a href="#introduction"><span class="secno">1</span> <span class="content">Introduction</span></a>
<li>
<a href="#values"><span class="secno">2</span> <span class="content"> Values and Interactions</span></a>
<ol class="toc">
<li><a href="#placement"><span class="secno">2.1</span> <span class="content"> Module Interactions</span></a>
<li><a href="#value-types"><span class="secno">2.2</span> <span class="content"> Value Types</span></a>
<li><a href="#animations"><span class="secno">2.3</span> <span class="content">Animated Values</span></a>
</ol>
<li>
<a href="#backgrounds"><span class="secno">3</span> <span class="content"> Backgrounds</span></a>
<ol class="toc">
<li><a href="#layering"><span class="secno">3.1</span> <span class="content"> Layering Multiple Background Images</span></a>
<li><a href="#background-color"><span class="secno">3.2</span> <span class="content">Base Color: the <span class="property">background-color</span> property</span></a>
<li><a href="#background-image"><span class="secno">3.3</span> <span class="content">Image Sources: the <span class="property">background-image</span> property</span></a>
<li><a href="#background-repeat"><span class="secno">3.4</span> <span class="content">Tiling Images: the <span class="property">background-repeat</span> property</span></a>
<li><a href="#background-attachment"><span class="secno">3.5</span> <span class="content">Affixing Images: the <span class="property">background-attachment</span> property</span></a>
<li><a href="#background-position"><span class="secno">3.6</span> <span class="content">Positioning Images: the <span class="property">background-position</span> property</span></a>
<li><a href="#background-clip"><span class="secno">3.7</span> <span class="content">Painting Area: the <span class="property">background-clip</span> property</span></a>
<li><a href="#background-origin"><span class="secno">3.8</span> <span class="content">Positioning Area: the <span class="property">background-origin</span> property</span></a>
<li><a href="#background-size"><span class="secno">3.9</span> <span class="content">Sizing Images: the <span class="property">background-size</span> property</span></a>
<li><a href="#background"><span class="secno">3.10</span> <span class="content">Backgrounds Shorthand: the <span class="property">background</span> property</span></a>
<li>
<a href="#special-backgrounds"><span class="secno">3.11</span> <span class="content"> Backgrounds of Special Elements</span></a>
<ol class="toc">
<li><a href="#root-background"><span class="secno">3.11.1</span> <span class="content"> The Canvas Background and the Root Element</span></a>
<li><a href="#body-background"><span class="secno">3.11.2</span> <span class="content"> The Canvas Background and the HTML <body> Element</span></a>
<li><a href="#first-line-background"><span class="secno">3.11.3</span> <span class="content"> The <span class="css">::first-line</span> Pseudo-element‘s Background</span></a>
</ol>
</ol>
<li>
<a href="#borders"><span class="secno">4</span> <span class="content"> Borders</span></a>
<ol class="toc">
<li><a href="#border-color"><span class="secno">4.1</span> <span class="content">Line Colors: the <span class="property">border-color</span> properties</span></a>
<li><a href="#border-style"><span class="secno">4.2</span> <span class="content">Line Patterns: the <span class="property">border-style</span> properties</span></a>
<li><a href="#border-width"><span class="secno">4.3</span> <span class="content">Line Thickness: the <span class="property">border-width</span> properties</span></a>
<li><a href="#border-shorthands"><span class="secno">4.4</span> <span class="content">Border Shorthand Properties</span></a>
</ol>
<li>
<a href="#corners"><span class="secno">5</span> <span class="content">Rounded Corners</span></a>
<ol class="toc">
<li><a href="#border-radius"><span class="secno">5.1</span> <span class="content">Curve Radii: the <span class="property">border-radius</span> properties</span></a>
<li><a href="#corner-shaping"><span class="secno">5.2</span> <span class="content">Corner Shaping</span></a>
<li><a href="#corner-clipping"><span class="secno">5.3</span> <span class="content">Corner Clipping</span></a>
<li><a href="#corner-transitions"><span class="secno">5.4</span> <span class="content">Color and Style Transitions</span></a>
<li><a href="#corner-overlap"><span class="secno">5.5</span> <span class="content">Overlapping Curves</span></a>
<li><a href="#border-radius-tables"><span class="secno">5.6</span> <span class="content">Effect on Tables</span></a>
</ol>
<li>
<a href="#border-images"><span class="secno">6</span> <span class="content">Border Images</span></a>
<ol class="toc">
<li><a href="#border-image-source"><span class="secno">6.1</span> <span class="content">Image Source: the <span class="property">border-image-source</span> property</span></a>
<li><a href="#border-image-slice"><span class="secno">6.2</span> <span class="content">Image Slicing: the <span class="property">border-image-slice</span> property</span></a>
<li><a href="#border-image-width"><span class="secno">6.3</span> <span class="content">Drawing Areas: the <span class="property">border-image-width</span> property</span></a>
<li><a href="#border-image-outset"><span class="secno">6.4</span> <span class="content">Edge Overhang: the <span class="property">border-image-outset</span> property</span></a>
<li><a href="#border-image-repeat"><span class="secno">6.5</span> <span class="content">Image Tiling: the <span class="property">border-image-repeat</span> property</span></a>
<li><a href="#border-image-process"><span class="secno">6.6</span> <span class="content"> Drawing the Border Image</span></a>
<li><a href="#border-image"><span class="secno">6.7</span> <span class="content">Border Image Shorthand: the <span class="property">border-image</span> property</span></a>
<li><a href="#border-image-tables"><span class="secno">6.8</span> <span class="content">Effect on Tables</span></a>
</ol>
<li>
<a href="#misc"><span class="secno">7</span> <span class="content">Miscellaneous Effects</span></a>
<ol class="toc">
<li>
<a href="#box-shadow"><span class="secno">7.1</span> <span class="content">Drop Shadows: the <span class="property">box-shadow</span> property</span></a>
<ol class="toc">
<li><a href="#shadow-shape"><span class="secno">7.1.1</span> <span class="content"> Shadow Shape, Spread, and Knockout</span></a>
<li><a href="#shadow-blur"><span class="secno">7.1.2</span> <span class="content"> Blurring Shadow Edges</span></a>
<li><a href="#shadow-layers"><span class="secno">7.1.3</span> <span class="content"> Layering, Layout, and Other Details</span></a>
</ol>
</ol>
<li>
<a href="#definitions"><span class="secno">8</span> <span class="content">Definitions</span></a>
<ol class="toc">
<li><a href="#glossary"><span class="secno">8.1</span> <span class="content">Glossary</span></a>
<li>
<a href="#levels"><span class="secno">8.2</span> <span class="content">Levels</span></a>
<ol class="toc">
<li><a href="#level-1"><span class="secno">8.2.1</span> <span class="content">Level 1</span></a>
<li><a href="#level-2"><span class="secno">8.2.2</span> <span class="content">Level 2</span></a>
<li><a href="#level-3"><span class="secno">8.2.3</span> <span class="content">Level 3</span></a>
</ol>
</ol>
<li>
<a href="#changes"><span class="secno">9</span> <span class="content"> Changes</span></a>
<ol class="toc">
<li><a href="#changes-2017-10"><span class="secno">9.1</span> <span class="content"> Changes since the 17 October 2017 Candidate Recommendation</span></a>
<li><a href="#changes-2014-09"><span class="secno">9.2</span> <span class="content"> Changes since the 9 September 2014 Candidate Recommendation</span></a>
<li><a href="#changes-2014-02"><span class="secno">9.3</span> <span class="content"> Changes since the 4 February 2014 Last Call Working Draft</span></a>
<li><a href="#changes-2012-07"><span class="secno">9.4</span> <span class="content"> Changes since the 24 July 2012 Candidate Recommendation</span></a>
<li><a href="#changes-2012-04"><span class="secno">9.5</span> <span class="content"> Changes since the 17 April 2012 Candidate Recommendation</span></a>
<li><a href="#changes-2012LC"><span class="secno">9.6</span> <span class="content"> Changes since the 14 February 2012 “Last Call” Working Draft</span></a>
<li><a href="#changes-2011"><span class="secno">9.7</span> <span class="content"> Changes Since the 15 February 2011 Candidate Recommendation</span></a>
<li><a href="#changes-2009"><span class="secno">9.8</span> <span class="content"> Changes Since the 17 December 2009 Candidate Recommendation</span></a>
</ol>
<li><a href="#acknowledgments"><span class="secno">10</span> <span class="content">Acknowledgments</span></a>
<li>
<a href="#conformance"><span class="secno"></span> <span class="content"> Conformance</span></a>
<ol class="toc">
<li><a href="#document-conventions"><span class="secno"></span> <span class="content"> Document conventions</span></a>
<li><a href="#conform-classes"><span class="secno"></span> <span class="content"> Conformance classes</span></a>
<li>
<a href="#conform-responsible"><span class="secno"></span> <span class="content"> Requirements for Responsible Implementation of CSS</span></a>
<ol class="toc">
<li><a href="#conform-partial"><span class="secno"></span> <span class="content"> Partial Implementations</span></a>
<li><a href="#conform-future-proofing"><span class="secno"></span> <span class="content"> Implementations of Unstable and Proprietary Features</span></a>
<li><a href="#conform-testing"><span class="secno"></span> <span class="content"> Implementations of CR-level Features</span></a>
</ol>
<li><a href="#cr-exit-criteria"><span class="secno"></span> <span class="content"> CR exit criteria</span></a>
</ol>
<li>
<a href="#index"><span class="secno"></span> <span class="content">Index</span></a>
<ol class="toc">
<li><a href="#index-defined-here"><span class="secno"></span> <span class="content">Terms defined by this specification</span></a>
<li><a href="#index-defined-elsewhere"><span class="secno"></span> <span class="content">Terms defined by reference</span></a>
</ol>
<li>
<a href="#references"><span class="secno"></span> <span class="content">References</span></a>
<ol class="toc">
<li><a href="#normative"><span class="secno"></span> <span class="content">Normative References</span></a>
<li><a href="#informative"><span class="secno"></span> <span class="content">Informative References</span></a>
</ol>
<li><a href="#property-index"><span class="secno"></span> <span class="content">Property Index</span></a>
</ol>
</nav>
<main>
<h2 class="heading settled" data-level="1" id="introduction"><span class="secno">1. </span><span class="content">Introduction</span><a class="self-link" href="#introduction"></a></h2>
<p><em>This subsection is not normative.</em> </p>
<p>When elements are rendered according to the <a href="https://www.w3.org/TR/CSS2/box.html">CSS box model</a> <a data-link-type="biblio" href="#biblio-css2">[CSS2]</a>,
each element is either not displayed at all, or formatted as one
or more rectangular boxes. Each box has a rectangular content
area, a band of padding around the content, a border around the
padding, and a margin outside the border. (The margin may actually be
negative, but margins have no influence on the background and border.) </p>
<div class="figure">
<p><img alt="Diagram of a typical box, showing the
content, padding, border and margin areas" src="images/box.png"> </p>
<p class="caption">The various areas and edges of a typical box.
(This diagram is explained in the CSS2.1 Box Model chapter <a data-link-type="biblio" href="#biblio-css2">[CSS2]</a>.) </p>
</div>
<p>The properties of this module deal with the decoration of the border
area and with the background of the content, padding and border areas.
Additionally the box may be given a "drop-shadow" effect with the <a class="property" data-link-type="propdesc" href="#propdef-box-shadow" id="ref-for-propdef-box-shadow①">box-shadow</a> property. </p>
<p>If an element is broken into multiple boxes, <a class="property" data-link-type="propdesc" href="https://www.w3.org/TR/css3-break/#propdef-box-decoration-break" id="ref-for-propdef-box-decoration-break">box-decoration-break</a> <a data-link-type="biblio" href="#biblio-css3-break">[CSS3-BREAK]</a> defines how the borders and background are divided over the various boxes.
(An element can result in more than one box if it is broken at the
end of a line, at the end of a column or at the end of a page; and
continued in the next line, column or page.) </p>
<p>The relative stacking order of backgrounds, borders, and shadows
is given in this module. For how these layers interact with other
rendered content, see Appendix E “Elaborate description of Stacking
Contexts” in <a data-link-type="biblio" href="#biblio-css2">[CSS2]</a>. </p>
<h2 class="heading settled" data-level="2" id="values"><span class="secno">2. </span><span class="content"> Values and Interactions</span><a class="self-link" href="#values"></a></h2>
<p>This specification follows the <a href="https://www.w3.org/TR/CSS2/about.html#property-defs">CSS property definition conventions</a> from <a data-link-type="biblio" href="#biblio-css2">[CSS2]</a> using the <a href="https://www.w3.org/TR/css-values-3/#value-defs">value definition syntax</a> from <a data-link-type="biblio" href="#biblio-css-values-3">[CSS-VALUES-3]</a>.
Value types not defined in this specification are defined in CSS Values & Units <a data-link-type="biblio" href="#biblio-css-values-3">[CSS-VALUES-3]</a>.
Other CSS modules may expand the definitions of these value types.</p>
<p>In addition to the property-specific values listed in their definitions,
all properties defined in this specification
also accept the <a data-link-type="dfn" href="https://www.w3.org/TR/css3-values/#css-wide-keywords" id="ref-for-css-wide-keywords">CSS-wide keywords</a> keywords as their property value.
For readability they have not been repeated explicitly.</p>
<h3 class="heading settled" data-level="2.1" id="placement"><span class="secno">2.1. </span><span class="content"> Module Interactions</span><a class="self-link" href="#placement"></a></h3>
<p>This module replaces and extends the background and border
features defined in <a data-link-type="biblio" href="#biblio-css2">[CSS2]</a> sections 8.5 and 14.2. </p>
<p>All properties in this module apply to the <a href="https://www.w3.org/TR/CSS2/selector.html#first-letter"><code>::first-letter</code></a> pseudo-element. The <a href="#backgrounds">background properties</a> and <a href="#corners">border-radius properties</a> also apply to the <a href="https://www.w3.org/TR/CSS2/selector.html#first-line-pseudo"><code>::first-line</code></a> pseudo-element. The UA may (but is not required to) apply the <a class="property" data-link-type="propdesc" href="#propdef-border-image" id="ref-for-propdef-border-image">border-image</a> or <a class="property" data-link-type="propdesc" href="#propdef-box-shadow" id="ref-for-propdef-box-shadow②">box-shadow</a> properties to <code>::first-line</code>. The UA must not apply the <a href="#borders">border-color/style/width properties</a> to <code>::first-line</code>. <a data-link-type="biblio" href="#biblio-css2">[CSS2]</a> </p>
<h3 class="heading settled" data-level="2.2" id="value-types"><span class="secno">2.2. </span><span class="content"> Value Types</span><a class="self-link" href="#value-types"></a></h3>
<p>The <dfn class="dfn-paneled css" data-dfn-type="type" data-export="" id="typedef-image"><a class="production css" data-link-type="type" href="#typedef-image" id="ref-for-typedef-image"><image></a></dfn> value type is defined by this
specification as <code class="prod"><a class="production css" data-link-type="type" href="#typedef-image" id="ref-for-typedef-image①"><image></a> = <a class="production css" data-link-type="type" href="https://www.w3.org/TR/CSS22/syndata.html#value-def-uri" id="ref-for-value-def-uri"><uri></a></code>. Other value types are defined in
CSS Level 2 Revision 1 <a data-link-type="biblio" href="#biblio-css2">[CSS2]</a>.
Other CSS modules may expand the definitions of these value types: for
example <a data-link-type="biblio" href="#biblio-css3color">[CSS3COLOR]</a>, when combined with this module, expands the
definition of the <a class="production css" data-link-type="type" href="https://www.w3.org/TR/css3-color/#valuea-def-color" id="ref-for-valuea-def-color" title="Expands to: indigo | gold | firebrick | indianred | yellow | darkolivegreen | darkseagreen | slategrey | chocolate | darkslategrey | mediumvioletred | mediumorchid | silver | chartreuse | mediumblue | black | springgreen | crimson | lightsalmon | brown | turquoise | olivedrab | lawngreen | cyan | transparent | skyblue | gray | darkturquoise | goldenrod | darkgreen | darkviolet | darkgray | lightpink | teal | darkmagenta | lightgoldenrodyellow | lavender | yellowgreen | thistle | violet | navy | darkblue | dimgrey | orchid | blue | ghostwhite | honeydew | cornflowerblue | purple | darkkhaki | mediumpurple | cornsilk | red | bisque | slategray | darkcyan | khaki | wheat | deepskyblue | rebeccapurple | darkred | steelblue | aliceblue | lightslategrey | gainsboro | mediumturquoise | floralwhite | coral | aqua | lightcyan | darksalmon | beige | azure | lightsteelblue | greenyellow | fuchsia | lightseagreen | sienna | lightcoral | orangered | navajowhite | lime | palegreen | mistyrose | seashell | mediumspringgreen | royalblue | papayawhip | blanchedalmond | peru | aquamarine | white | darkslategray | lightgray | ivory | darkgoldenrod | currentcolor | lemonchiffon | burlywood | orange | forestgreen | darkgrey | olive | mintcream | antiquewhite | darkorange | hotpink | moccasin | limegreen | saddlebrown | grey | darkslateblue | lightskyblue | deeppink | plum | lightgrey | dodgerblue | maroon | sandybrown | magenta | tan | rosybrown | pink | lightblue | palevioletred | mediumseagreen | slateblue | dimgray | powderblue | seagreen | snow | mediumslateblue | midnightblue | paleturquoise | palegoldenrod | whitesmoke | darkorchid | salmon | lightslategray | oldlace | lightgreen | tomato | cadetblue | lightyellow | lavenderblush | linen | mediumaquamarine | green | blueviolet | peachpuff"><color></a> value type as used in this specification.
Similarly, <a data-link-type="biblio" href="#biblio-css3-images">[CSS3-IMAGES]</a>, when combined with this module,
expands the definition of <a class="production css" data-link-type="type" href="#typedef-image" id="ref-for-typedef-image②"><image></a> as used in this specification. </p>
<p>In addition to the property-specific values listed in their definitions,
all properties defined in this specification also accept the <a href="https://www.w3.org/TR/CSS2/cascade.html#value-def-inherit">inherit</a> keyword as their property value. For readability it has not been repeated
explicitly. </p>
<h3 class="heading settled" data-level="2.3" id="animations"><span class="secno">2.3. </span><span class="content">Animated Values</span><a class="self-link" href="#animations"></a></h3>
<p> It is expected that CSS will include ways to
animate transitions between styles. (The
section <a U0003Cblockquote="" href="https://www.w3.org/TR/css3-transitions/#animatable-types"> </a></p>
<p><a U0003Cblockquote="" href="https://www.w3.org/TR/css3-transitions/#animatable-types">“Animation of property types”</a> of the <cite>CSS Transitions
module</cite> <a data-link-type="biblio" href="#biblio-css3-transitions">[CSS3-TRANSITIONS]</a> is expected to define how different
kinds of values are interpolated during a transition.) In anticipation
of that, this module includes a line “Animatable” for each property,
which specifies whether and how values of the property can be animated.</p>
<h2 class="heading settled" data-level="3" id="backgrounds"><span class="secno">3. </span><span class="content"> Backgrounds</span><a class="self-link" href="#backgrounds"></a></h2>
<p>Each box has a background layer that may be fully transparent (the
default), or filled with a color and/or one or more images. The background
properties specify what color (<a class="property" data-link-type="propdesc" href="#propdef-background-color" id="ref-for-propdef-background-color">background-color</a>)
and images (<a class="property" data-link-type="propdesc" href="#propdef-background-image" id="ref-for-propdef-background-image">background-image</a>) to use,
and how they are sized, positioned, tiled, etc. </p>
<p>The background properties are not inherited, but the parent box’s
background will shine through by default because of the initial <span class="css">transparent</span> value on <a class="property" data-link-type="propdesc" href="#propdef-background-color" id="ref-for-propdef-background-color①">background-color</a>. </p>
<h3 class="heading settled" data-level="3.1" id="layering"><span class="secno">3.1. </span><span class="content"> Layering Multiple Background Images</span><a class="self-link" href="#layering"></a></h3>
<p>The background of a box can have multiple <span class="index">layers</span> in CSS3. The number
of layers is determined by the number of comma-separated values in the <a class="property" data-link-type="propdesc" href="#propdef-background-image" id="ref-for-propdef-background-image①">background-image</a> property. Note that a value of <a class="css" data-link-type="maybe" href="#valdef-background-image-none" id="ref-for-valdef-background-image-none">none</a> still creates
a layer. </p>
<p>Each of the images is sized, positioned, and tiled according to
the corresponding value in the other background properties. The lists
are matched up from the first value: excess values at the end are not
used. If a property doesn’t have enough comma-separated values to match
the number of layers, the <span>UA</span> must calculate its used
value by repeating
the list of values until there are enough. </p>
<div class="example" id="example-077d5951">
<a class="self-link" href="#example-077d5951"></a>
<p>For example, this set of declarations: </p>
<pre>background-image: url(flower.png), url(ball.png), url(grass.png);
background-position: center center, 20% 80%, top left, bottom right;
background-origin: border-box, content-box;
background-repeat: no-repeat;
</pre>
<p>has exactly the same effect as this set with the extra position
dropped and the missing values for <a class="property" data-link-type="propdesc" href="#propdef-background-origin" id="ref-for-propdef-background-origin">background-origin</a> and <a class="property" data-link-type="propdesc" href="#propdef-background-repeat" id="ref-for-propdef-background-repeat">background-repeat</a> filled in (emphasized for clarity): </p>
<pre>background-image: url(flower.png), url(ball.png), url(grass1.png);
background-position: center center, 20% 80%, top left;
background-origin: border-box, content-box<strong>, border-box</strong>;
background-repeat: no-repeat<strong>, no-repeat, no-repeat</strong>;
</pre>
</div>
<p>The first image in the list is the layer closest to the user,
the next one is painted behind the first, and so on. The background
color, if present, is painted below all of the other layers. </p>
<p class="note" role="note">Note that the <a href="#border-images">border-image properties</a> can also define a background image, which, if present, is painted on top of
the background created by the background properties. </p>
<h3 class="heading settled" data-level="3.2" id="background-color"><span class="secno">3.2. </span><span class="content">Base Color: the <a class="property" data-link-type="propdesc" href="#propdef-background-color" id="ref-for-propdef-background-color②">background-color</a> property</span><span id="the-background-color"></span><a class="self-link" href="#background-color"></a></h3>
<table class="propdef">
<tbody>
<tr>
<th>Name:
<td><dfn class="dfn-paneled css" data-dfn-type="property" data-export="" id="propdef-background-color">background-color</dfn>
<tr>
<th><a href="#values">Value</a>:
<td><a class="production css" data-link-type="type" href="https://www.w3.org/TR/css3-color/#valuea-def-color" id="ref-for-valuea-def-color①" title="Expands to: indigo | gold | firebrick | indianred | yellow | darkolivegreen | darkseagreen | slategrey | chocolate | darkslategrey | mediumvioletred | mediumorchid | silver | chartreuse | mediumblue | black | springgreen | crimson | lightsalmon | brown | turquoise | olivedrab | lawngreen | cyan | transparent | skyblue | gray | darkturquoise | goldenrod | darkgreen | darkviolet | darkgray | lightpink | teal | darkmagenta | lightgoldenrodyellow | lavender | yellowgreen | thistle | violet | navy | darkblue | dimgrey | orchid | blue | ghostwhite | honeydew | cornflowerblue | purple | darkkhaki | mediumpurple | cornsilk | red | bisque | slategray | darkcyan | khaki | wheat | deepskyblue | rebeccapurple | darkred | steelblue | aliceblue | lightslategrey | gainsboro | mediumturquoise | floralwhite | coral | aqua | lightcyan | darksalmon | beige | azure | lightsteelblue | greenyellow | fuchsia | lightseagreen | sienna | lightcoral | orangered | navajowhite | lime | palegreen | mistyrose | seashell | mediumspringgreen | royalblue | papayawhip | blanchedalmond | peru | aquamarine | white | darkslategray | lightgray | ivory | darkgoldenrod | currentcolor | lemonchiffon | burlywood | orange | forestgreen | darkgrey | olive | mintcream | antiquewhite | darkorange | hotpink | moccasin | limegreen | saddlebrown | grey | darkslateblue | lightskyblue | deeppink | plum | lightgrey | dodgerblue | maroon | sandybrown | magenta | tan | rosybrown | pink | lightblue | palevioletred | mediumseagreen | slateblue | dimgray | powderblue | seagreen | snow | mediumslateblue | midnightblue | paleturquoise | palegoldenrod | whitesmoke | darkorchid | salmon | lightslategray | oldlace | lightgreen | tomato | cadetblue | lightyellow | lavenderblush | linen | mediumaquamarine | green | blueviolet | peachpuff"><color></a>
<tr>
<th>Initial:
<td>transparent
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>the computed color
<tr>
<th>Animatable:
<td>as <a href="https://www.w3.org/TR/css3-transitions/#animtype-color">color</a>
</table>
<p>This property sets the <span class="index" title="color!!background">background color</span> of an element. The
color is drawn behind any background images. </p>
<div class="example" id="example-bc7e40c3">
<a class="self-link" href="#example-bc7e40c3"></a>
<p>Example: </p>
<pre>h1 { background-color: #F00 } /* Sets background to red. */</pre>
</div>
<p>The background color is clipped according to the <a class="property" data-link-type="propdesc" href="#propdef-background-clip" id="ref-for-propdef-background-clip">background-clip</a> value associated with the bottom-most background image layer. </p>
<h3 class="heading settled" data-level="3.3" id="background-image"><span class="secno">3.3. </span><span class="content">Image Sources: the <a class="property" data-link-type="propdesc" href="#propdef-background-image" id="ref-for-propdef-background-image②">background-image</a> property</span><span id="the-background-image"></span><a class="self-link" href="#background-image"></a></h3>
<table class="propdef">
<tbody>
<tr>
<th>Name:
<td><dfn class="dfn-paneled css" data-dfn-type="property" data-export="" id="propdef-background-image">background-image</dfn>
<tr>
<th><a href="#values">Value</a>:
<td><a class="production css" data-link-type="type" href="#typedef-bg-image" id="ref-for-typedef-bg-image"><bg-image></a>#
<tr>
<th>Initial:
<td>none
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>as specified, but with URIs made absolute
<tr>
<th>Animatable:
<td>no
</table>
<p>This property sets the background image(s) of an element. Images
are drawn with the first specified one on top (closest to the user)
and each subsequent image behind the previous one.
Where </p>
<pre class="prod"><dfn class="dfn-paneled" data-dfn-type="type" data-export="" id="typedef-bg-image"><a class="production" data-link-type="type" href="#typedef-bg-image" id="ref-for-typedef-bg-image①"><bg-image></a></dfn> = <a class="production" data-link-type="type" href="#typedef-image" id="ref-for-typedef-image③"><image></a> <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one">|</a> none</pre>
<p>A value of <dfn class="dfn-paneled css" data-dfn-for="background-image" data-dfn-type="value" data-export="" id="valdef-background-image-none">none</dfn> counts as an image layer but draws
nothing. An image that is empty (zero width or zero height), that
fails to download, or that cannot be displayed (e.g., because it is
not in a supported image format) likewise counts as a layer but
draws nothing. </p>
<p>See the section <a href="#layering">“Layering multiple background
images”</a> for how <a class="property" data-link-type="propdesc" href="#propdef-background-image" id="ref-for-propdef-background-image③">background-image</a> interacts with other
comma-separated background properties to form each background image
layer. </p>
<p>When setting a background image, authors should also specify a <a class="property" data-link-type="propdesc" href="#propdef-background-color" id="ref-for-propdef-background-color③">background-color</a> that will preserve contrast with the text for
when the image is unavailable. </p>
<p>For accessibility reasons, authors should not use background images
as the sole method of conveying important information.
See <a href="https://www.w3.org/TR/2008/NOTE-WCAG20-TECHS-20081211/F3">Web
Content Accessibility Guideline F3</a> <a data-link-type="biblio" href="#biblio-wcag20">[WCAG20]</a>. Images are not
accessible in non-graphical presentations, and background images
specifically might be turned off in high-contrast display modes. </p>
<p class="note" role="note">Note that stylistic foreground images can be provided
in CSS with the <a href="https://www.w3.org/TR/CSS2/generate.html#content">content</a> property. (Semantically-important foreground images should be provided
in the document markup, e.g. with the <img> tag in HTML.)</p>
<p class="note" role="note"><a href="https://www.w3.org/TR/media-frags/#naming-space">Media fragments</a> can be used to display a portion of an image. The <a href="https://www.w3.org/TR/css3-images/">CSS Images</a> module
will provide fallback syntax for image formats and include additional
controls for image display. </p>
<div class="example" id="example-83b90671">
<a class="self-link" href="#example-83b90671"></a>
<p>Some examples specifying background images:</p>
<pre>body { background-image: url("marble.svg") }
p { background-image: none }
div { background-image: url(tl.png), url(tr.png) }
</pre>
</div>
<p class="note" role="note">Implementations may optimize by not downloading and
drawing images that are not visible (e.g., because they are behind
other, fully opaque images). </p>
<h3 class="heading settled" data-level="3.4" id="background-repeat"><span class="secno">3.4. </span><span class="content">Tiling Images: the <a class="property" data-link-type="propdesc" href="#propdef-background-repeat" id="ref-for-propdef-background-repeat①">background-repeat</a> property</span><span id="the-background-repeat"></span><a class="self-link" href="#background-repeat"></a></h3>
<table class="propdef">
<tbody>
<tr>
<th>Name:
<td><dfn class="dfn-paneled css" data-dfn-type="property" data-export="" id="propdef-background-repeat">background-repeat</dfn>
<tr>
<th><a href="#values">Value</a>:
<td><a class="production css" data-link-type="type" href="#typedef-repeat-style" id="ref-for-typedef-repeat-style"><repeat-style></a>#
<tr>
<th>Initial:
<td>repeat
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>A list, each item consisting of:
two keywords, one per dimension
<tr>
<th>Animatable:
<td>no
</table>
<p>Specifies how background images are tiled after they have been <a href="#the-background-size">sized</a> and <a href="#the-background-position">positioned</a>.
Where </p>
<pre class="prod"><dfn class="dfn-paneled" data-dfn-type="type" data-export="" id="typedef-repeat-style"><a class="production" data-link-type="type" href="#typedef-repeat-style" id="ref-for-typedef-repeat-style①"><repeat-style></a></dfn> = repeat-x <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one①">|</a> repeat-y <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one②">|</a> [repeat <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one③">|</a> space <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one④">|</a> round <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one⑤">|</a> no-repeat]<a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#mult-num-range" id="ref-for-mult-num-range">{1,2}</a></pre>
<p>Single values for <a class="production css" data-link-type="type" href="#typedef-repeat-style" id="ref-for-typedef-repeat-style②"><repeat-style></a> have the following
meanings: </p>
<dl>
<dt><dfn class="dfn-paneled css" data-dfn-for="background-repeat" data-dfn-type="value" data-export="" id="valdef-background-repeat-repeat-x">repeat-x</dfn>
<dd> Computes to <span class="css">repeat no-repeat</span>.
<dt><dfn class="dfn-paneled css" data-dfn-for="background-repeat" data-dfn-type="value" data-export="" id="valdef-background-repeat-repeat-y">repeat-y</dfn>
<dd> Computes to <span class="css">no-repeat repeat</span>.
<dt><a class="css" data-link-type="maybe" href="#valdef-background-repeat-repeat" id="ref-for-valdef-background-repeat-repeat">repeat</a>
<dd> Computes to <span class="css">repeat repeat</span>.
<dt><a class="css" data-link-type="maybe" href="#valdef-background-repeat-space" id="ref-for-valdef-background-repeat-space">space</a>
<dd> Computes to <span class="css">space space</span>
<dt><a class="css" data-link-type="maybe" href="#valdef-background-repeat-round" id="ref-for-valdef-background-repeat-round">round</a>
<dd> Computes to <span class="css">round round</span>
<dt><a class="css" data-link-type="maybe" href="#valdef-background-repeat-no-repeat" id="ref-for-valdef-background-repeat-no-repeat">no-repeat</a>
<dd> Computes to <span class="css">no-repeat no-repeat</span>
</dl>
<p>If a <a class="production css" data-link-type="type" href="#typedef-repeat-style" id="ref-for-typedef-repeat-style③"><repeat-style></a> value has two keywords, the first
one is for the horizontal direction, the second for the vertical one,
as follows: </p>
<dl>
<dt><dfn class="dfn-paneled css" data-dfn-for="background-repeat" data-dfn-type="value" data-export="" id="valdef-background-repeat-repeat">repeat</dfn>
<dd> The image is repeated in this direction as often as needed to cover
the <span class="index">background painting area</span>.
<dt><dfn class="dfn-paneled css" data-dfn-for="background-repeat" data-dfn-type="value" data-export="" id="valdef-background-repeat-space">space</dfn>
<dd> The image is repeated as often as will fit within the <span class="index">background positioning area</span> without being
clipped and then the images are spaced out to fill the area. The
first and last images touch the edges of the area. If the <span class="index">background
painting area</span> is larger than the background positioning area, then
the pattern repeats to fill the background painting area.
The value of <a class="property" data-link-type="propdesc" href="#propdef-background-position" id="ref-for-propdef-background-position">background-position</a> for this direction
is ignored, unless there is not enough space for two copies of the
image in this direction, in which case only one image is placed and <a class="property" data-link-type="propdesc" href="#propdef-background-position" id="ref-for-propdef-background-position①">background-position</a> determines its position in this
direction.
<dt><dfn class="dfn-paneled css" data-dfn-for="background-repeat" data-dfn-type="value" data-export="" id="valdef-background-repeat-round">round</dfn>
<dd> The image is repeated as often as will fit within the <span class="index">background positioning area.</span> If it doesn’t
fit a whole number of times, it is rescaled so that it does.
See the formula under <a class="property" data-link-type="propdesc" href="#propdef-background-size" id="ref-for-propdef-background-size">background-size</a>. If the <span class="index">background
painting area</span> is larger than the background positioning area, then
the pattern repeats to fill the background painting area.
<dt><dfn class="dfn-paneled css" data-dfn-for="background-repeat" data-dfn-type="value" data-export="" id="valdef-background-repeat-no-repeat">no-repeat</dfn>
<dd> The image is placed once and not repeated in this direction.
</dl>
<p>Unless one of the two keywords is <a class="css" data-link-type="maybe" href="#valdef-background-repeat-no-repeat" id="ref-for-valdef-background-repeat-no-repeat①">no-repeat</a>, the
whole background painting area will be tiled, i.e., not just one
vertical strip and one horizontal strip. </p>
<div class="example" id="example-e247d720">
<a class="self-link" href="#example-e247d720"></a>
<p style="display:none">Example(s): </p>
<pre>body {
background: white url("pendant.png");
background-repeat: repeat-y;
background-position: center;
}
</pre>
<div class="figure">
<p><img alt="A centered background image, with
copies repeated up and down the border, padding and content
areas." src="images/bg-repeat.png"> </p>
<p class="caption">The effect of <a class="css" data-link-type="maybe" href="#valdef-background-repeat-repeat-y" id="ref-for-valdef-background-repeat-repeat-y">repeat-y</a>: One copy
of the background image is centered, and other copies are put above
and below it to make a vertical band behind the element. </p>
</div>
</div>
<div class="example" id="example-6efd740b">
<a class="self-link" href="#example-6efd740b"></a>
<p style="display:none">Example(s): </p>
<pre>body {
background-image: url(dot.png) white;
background-repeat: space
}
</pre>
<div class="figure">
<p><img alt="Image of an element with a dotted background" src="images/bg-space.png"> </p>
<p class="caption">The effect of <a class="css" data-link-type="maybe" href="#valdef-background-repeat-space" id="ref-for-valdef-background-repeat-space①">space</a>: the image of a dot is
tiled to cover the whole background and the images are equally
spaced. </p>
</div>
</div>
<p>See the section <a href="#layering">“Layering multiple background
images”</a> for how <a class="property" data-link-type="propdesc" href="#propdef-background-repeat" id="ref-for-propdef-background-repeat②">background-repeat</a> interacts with other
comma-separated background properties to form each background image
layer. </p>
<h3 class="heading settled" data-level="3.5" id="background-attachment"><span class="secno">3.5. </span><span class="content">Affixing Images: the <a class="property" data-link-type="propdesc" href="#propdef-background-attachment" id="ref-for-propdef-background-attachment">background-attachment</a> property</span><span id="the-background-attachment"></span><a class="self-link" href="#background-attachment"></a></h3>
<table class="propdef">
<tbody>
<tr>
<th>Name:
<td><dfn class="dfn-paneled css" data-dfn-type="property" data-export="" id="propdef-background-attachment">background-attachment</dfn>
<tr>
<th><a href="#values">Value</a>:
<td><a class="production css" data-link-type="type" href="#typedef-attachment" id="ref-for-typedef-attachment"><attachment></a>#
<tr>
<th>Initial:
<td>scroll
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>as specified
<tr>
<th>Animatable:
<td>no
</table>
<p>If background images are specified, this property specifies whether
they are fixed with regard to the <em class="index">viewport</em> (<a class="css" data-link-type="maybe" href="#valdef-background-attachment-fixed" id="ref-for-valdef-background-attachment-fixed">fixed</a>) or scroll along with the element (<a class="css" data-link-type="maybe" href="#valdef-background-attachment-scroll" id="ref-for-valdef-background-attachment-scroll">scroll</a>)
or its contents (<a class="css" data-link-type="maybe" href="#valdef-background-attachment-local" id="ref-for-valdef-background-attachment-local">local</a>). The property’s value is given as
a comma-separated list of <attachment> keywords where </p>
<pre class="prod"><dfn class="dfn-paneled" data-dfn-type="type" data-export="" id="typedef-attachment"><a class="production" data-link-type="type" href="#typedef-attachment" id="ref-for-typedef-attachment①"><attachment></a></dfn> = scroll <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one⑥">|</a> fixed <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one⑦">|</a> local</pre>
<dl>
<dt><dfn class="dfn-paneled css" data-dfn-for="background-attachment" data-dfn-type="value" data-export="" id="valdef-background-attachment-fixed">fixed</dfn>
<dd>The background is fixed with regard to the viewport. In paged
media where there is no viewport, a <a class="css" data-link-type="maybe" href="#valdef-background-attachment-fixed" id="ref-for-valdef-background-attachment-fixed①">fixed</a> background is fixed
with respect to the <a href="https://www.w3.org/TR/CSS2/page.html#page-box">page box</a> and therefore replicated on every page. <span class="note">Note that there is only one viewport per view.
Even if an element has a scrolling mechanism (see the <a class="property" data-link-type="propdesc" href="https://www.w3.org/TR/CSS22/visufx.html#propdef-overflow" id="ref-for-propdef-overflow">overflow</a> property <a data-link-type="biblio" href="#biblio-css2">[CSS2]</a>), a <a class="css" data-link-type="maybe" href="#valdef-background-attachment-fixed" id="ref-for-valdef-background-attachment-fixed②">fixed</a> background doesn’t move with the
element.</span>
<dt><dfn class="dfn-paneled css" data-dfn-for="background-attachment" data-dfn-type="value" data-export="" id="valdef-background-attachment-local">local</dfn>
<dd>The background is fixed with regard to the element’s contents:
if the element has a scrolling mechanism,
the background scrolls with the element’s contents,
and the <a data-link-type="dfn" href="#background-painting-area" id="ref-for-background-painting-area">background painting area</a> and <a data-link-type="dfn" href="#background-positioning-area" id="ref-for-background-positioning-area">background positioning area</a> are relative to the scrollable area of the element rather than to the border framing them.
Because the scrollable area does not include the border area,
for scrollable elements the <a class="css" data-link-type="maybe" href="#valdef-background-clip-border-box" id="ref-for-valdef-background-clip-border-box">border-box</a> value of <a class="property" data-link-type="propdesc" href="#propdef-background-clip" id="ref-for-propdef-background-clip①">background-clip</a> may be treated the same as <a class="css" data-link-type="maybe" href="#valdef-background-clip-padding-box" id="ref-for-valdef-background-clip-padding-box">padding-box</a>.
<dt><dfn class="dfn-paneled css" data-dfn-for="background-attachment" data-dfn-type="value" data-export="" id="valdef-background-attachment-scroll">scroll</dfn>
<dd>The background is fixed with regard to the element itself and
does not scroll with its contents. (It is effectively attached
to the element’s border.)
</dl>
<p>Even if the image is fixed, it is still only visible when it is in
the <em class="index">background painting area</em> of the element or otherwise
unclipped. (See <a href="#special-backgrounds"> “The backgrounds of
special elements”</a> for the cases when background images are not
clipped.) Thus, unless the image is tiled, it may be invisible. </p>
<div class="example" id="example-b9fb257b">
<a class="self-link" href="#example-b9fb257b"></a>
<p>This example creates an infinite vertical band that remains
“glued” to the viewport when the element is scrolled. </p>
<pre>body {
background: red url("pendant.gif");
background-repeat: repeat-y;
background-attachment: fixed;
}
</pre>
</div>
<p>User agents that do not support <a class="css" data-link-type="maybe" href="#valdef-background-attachment-fixed" id="ref-for-valdef-background-attachment-fixed③">fixed</a> backgrounds (for
example due to limitations of the hardware platform) should ignore
declarations with the keyword <a class="css" data-link-type="maybe" href="#valdef-background-attachment-fixed" id="ref-for-valdef-background-attachment-fixed④">fixed</a>. For example: </p>
<pre class="example" id="example-04d9c5ce"><a class="self-link" href="#example-04d9c5ce"></a>body {
/* For all UAs: */
background: white url(paper.png) scroll;
/* For UAs that do fixed backgrounds: */
background: white url(ledger.png) fixed;
}
h1 {
/* For all UAs: */
background: silver;
/* For UAs that do fixed backgrounds: */
background: url(stripe.png) fixed, white url(ledger.png) fixed;
}
</pre>
<p>See the section <a href="#layering">“Layering multiple background
images”</a> for how <a class="property" data-link-type="propdesc" href="#propdef-background-attachment" id="ref-for-propdef-background-attachment①">background-attachment</a> interacts with other
comma-separated background properties to form each background image
layer. </p>
<h3 class="heading settled" data-level="3.6" id="background-position"><span class="secno">3.6. </span><span class="content">Positioning Images: the <a class="property" data-link-type="propdesc" href="#propdef-background-position" id="ref-for-propdef-background-position②">background-position</a> property</span><span id="the-background-position"></span><a class="self-link" href="#background-position"></a></h3>
<table class="propdef">
<tbody>
<tr>
<th>Name:
<td><dfn class="dfn-paneled css" data-dfn-type="property" data-export="" id="propdef-background-position">background-position</dfn>
<tr>
<th><a href="#values">Value</a>:
<td><a class="production css" data-link-type="type" href="#typedef-bg-position" id="ref-for-typedef-bg-position"><bg-position></a>
<tr>
<th>Initial:
<td>0% 0%
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>refer to size of <span class="index">background positioning
area</span> <em>minus</em> size of background image; see text
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>A list, each item consisting of:
a pair of offsets (horizontal and vertical) from the top left origin
each given as a combination of an absolute length and a percentage
<tr>
<th>Animatable:
<td>as <a href="https://www.w3.org/TR/css3-transitions/#animtype-repeatable-list">repeatable list</a> of <a href="https://www.w3.org/TR/css3-transitions/#animtype-simple-list">simple list</a> of <a href="https://www.w3.org/TR/css3-transitions/#animtype-lpcalc">length, percentage, or calc</a>
</table>
<p>If background images have been specified, this property specifies
their initial position (after any <a href="#the-background-size">resizing</a>)
within their corresponding <span>background positioning area.</span> </p>
<p>Where </p>
<pre class="prod"><dfn class="dfn-paneled" data-dfn-type="type" data-export="" id="typedef-bg-position"><a class="production" data-link-type="type" href="#typedef-bg-position" id="ref-for-typedef-bg-position①"><bg-position></a></dfn> = [ [ left <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one⑧">|</a> center <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one⑨">|</a> right <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one①⓪">|</a> top <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one①①">|</a> bottom <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one①②">|</a> <a class="production" data-link-type="type" href="https://www.w3.org/TR/css3-values/#typedef-length-percentage" id="ref-for-typedef-length-percentage"><length-percentage></a> ]
<a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one①③">|</a>
[ left <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one①④">|</a> center <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one①⑤">|</a> right <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one①⑥">|</a> <a class="production" data-link-type="type" href="https://www.w3.org/TR/css3-values/#typedef-length-percentage" id="ref-for-typedef-length-percentage①"><length-percentage></a> ]
[ top <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one①⑦">|</a> center <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one①⑧">|</a> bottom <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one①⑨">|</a> <a class="production" data-link-type="type" href="https://www.w3.org/TR/css3-values/#typedef-length-percentage" id="ref-for-typedef-length-percentage②"><length-percentage></a> ]
<a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one②⓪">|</a>
[ center <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one②①">|</a> [ left <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one②②">|</a> right ] <a class="production" data-link-type="type" href="https://www.w3.org/TR/css3-values/#typedef-length-percentage" id="ref-for-typedef-length-percentage③"><length-percentage></a><a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#mult-opt" id="ref-for-mult-opt">?</a> ] <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-all" id="ref-for-comb-all">&&</a>
[ center <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one②③">|</a> [ top <a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#comb-one" id="ref-for-comb-one②④">|</a> bottom ] <a class="production" data-link-type="type" href="https://www.w3.org/TR/css3-values/#typedef-length-percentage" id="ref-for-typedef-length-percentage④"><length-percentage></a><a data-link-type="grammar" href="https://www.w3.org/TR/css3-values/#mult-opt" id="ref-for-mult-opt①">?</a> ]
]</pre>
<p>If only one value is specified, the second value is assumed to be <a class="css" data-link-type="maybe" href="#valdef-background-position-center" id="ref-for-valdef-background-position-center">center</a>. If two values are given, a <a class="production css" data-link-type="type" href="https://www.w3.org/TR/css3-values/#typedef-length-percentage" id="ref-for-typedef-length-percentage⑤"><length-percentage></a> as the first
value represents the horizontal position (or offset) and a <a class="production css" data-link-type="type" href="https://www.w3.org/TR/css3-values/#typedef-length-percentage" id="ref-for-typedef-length-percentage⑥"><length-percentage></a> as the second value represents the vertical position (or offset).
The <a class="production css" data-link-type="type" href="https://www.w3.org/TR/css3-values/#typedef-length-percentage" id="ref-for-typedef-length-percentage⑦"><length-percentage></a> values here represent an offset of the top left corner
of the background image from the top left corner of the background
positioning area. </p>
<p class="note" role="note">Note that a pair of keywords can be reordered while
a combination of keyword and length or percentage cannot.
So <span class="css">center left</span> is valid while <span class="css">50% left</span> is not. </p>
<p>If three or four values are given, then
each <a class="production css" data-link-type="type" href="https://www.w3.org/TR/css3-values/#typedef-length-percentage" id="ref-for-typedef-length-percentage⑧"><length-percentage></a> represents an offset and must be preceded by a keyword,
which specifies from which edge the offset is given. For example, <a class="css" data-link-type="propdesc" href="#propdef-background-position" id="ref-for-propdef-background-position③">background-position: bottom 10px right 20px</a> represents a <span class="css">10px</span> vertical offset up from the bottom edge and a <span class="css">20px</span> horizontal offset leftward from the right edge. If
three values are given, the missing offset is assumed to be zero. </p>
<p>Positive values represent an offset <em>inward</em> from the edge of
the background positioning area. Negative values represent an offset <em>outward</em> from the edge of the background positioning area. </p>
<div class="example" id="example-10f2c038">
<a class="self-link" href="#example-10f2c038"></a>
<p>The following declarations give the stated (horizontal, vertical)
offsets from the top left corner:</p>
<pre>background-position: left 10px top 15px; /* 10px, 15px */
background-position: left top ; /* 0px, 0px */
background-position: 10px 15px; /* 10px, 15px */
background-position: left 15px; /* 0px, 15px */
background-position: 10px top ; /* 10px, 0px */
background-position: left top 15px; /* 0px, 15px */
background-position: left 10px top ; /* 10px, 0px */</pre>
</div>
<dl>
<dt><dfn class="css" data-dfn-for="background-position" data-dfn-type="value" data-export="" id="valdef-background-position-percentage"><a class="production css" data-link-type="type" href="https://www.w3.org/TR/css3-values/#percentage-value" id="ref-for-percentage-value"><percentage></a><a class="self-link" href="#valdef-background-position-percentage"></a></dfn>
<dd>
<p>A percentage for the horizontal offset is relative to (<var>width of
background positioning area</var> - <var>width of background image</var>).
A percentage for the vertical offset is relative to (<var>height
of background
positioning area</var> - <var>height of background image</var>), where the
size of the image is the size given by <a class="property" data-link-type="propdesc" href="#propdef-background-size" id="ref-for-propdef-background-size①">background-size</a>. </p>
<div class="example" id="example-5e031c5b">
<a class="self-link" href="#example-5e031c5b"></a>
<p>For example, with a value pair of <span class="css">0% 0%</span>, the upper left
corner of the image is aligned with the upper left corner of, usually,
the box’s padding edge. A value pair of <span class="css">100% 100%</span> places
the lower right corner of the image in the lower right corner of the
area. With a value pair of <span class="css">75% 50%</span>, the point 75% across
and 50% down the image is to be placed at the point 75% across and 50%
down the area. </p>
<div class="figure">
<p><img alt="Diagram of image position within element" src="images/bg-pos.png"> </p>
<p class="caption">Diagram of the meaning of <a class="css" data-link-type="propdesc" href="#propdef-background-position" id="ref-for-propdef-background-position④">background-position: 75% 50%</a>. </p>
</div>
</div>
<dt><dfn class="css" data-dfn-for="background-position" data-dfn-type="value" data-export="" id="valdef-background-position-length"><a class="production css" data-link-type="type" href="https://www.w3.org/TR/css3-values/#length-value" id="ref-for-length-value" title="Expands to: em | vb | ch | cm | vh | vi | vw | ex | in | ic | pt | px | lh | pc | rem | rlh | vmax | advance measure | vmin | mm | cap | q"><length></a><a class="self-link" href="#valdef-background-position-length"></a></dfn>
<dd>A length value gives a fixed length as the offset. For example, with a
value pair of <span class="css">2cm 1cm</span>, the upper left corner of the image
is placed 2cm to the right and 1cm below the upper left corner of the
background positioning area.
<dt><dfn class="dfn-paneled css" data-dfn-for="background-position" data-dfn-type="value" data-export="" id="valdef-background-position-top"><a class="css" data-link-type="maybe" href="#valdef-background-position-top" id="ref-for-valdef-background-position-top">top</a></dfn>
<dd>Computes to <span class="css">0%</span> for the vertical position if one or two
values are given, otherwise specifies the top edge as the origin for the
next offset.
<dt><dfn class="dfn-paneled css" data-dfn-for="background-position" data-dfn-type="value" data-export="" id="valdef-background-position-right"><a class="css" data-link-type="maybe" href="#valdef-background-position-right" id="ref-for-valdef-background-position-right">right</a></dfn>
<dd>Computes to <span class="css">100%</span> for the horizontal position if one or two
values are given, otherwise specifies the right edge as the origin
for the next offset.
<dt><dfn class="dfn-paneled css" data-dfn-for="background-position" data-dfn-type="value" data-export="" id="valdef-background-position-bottom"><a class="css" data-link-type="maybe" href="#valdef-background-position-bottom" id="ref-for-valdef-background-position-bottom">bottom</a></dfn>
<dd>Computes to <span class="css">100%</span> for the vertical position if one or two
values are given, otherwise specifies the bottom edge as the origin
for the next offset.
<dt><dfn class="dfn-paneled css" data-dfn-for="background-position" data-dfn-type="value" data-export="" id="valdef-background-position-left"><a class="css" data-link-type="maybe" href="#valdef-background-position-left" id="ref-for-valdef-background-position-left">left</a></dfn>
<dd>Computes to <span class="css">0%</span> for the horizontal position if one or two
values are given, otherwise specifies the left edge as the origin
for the next offset.
<dt><dfn class="dfn-paneled css" data-dfn-for="background-position" data-dfn-type="value" data-export="" id="valdef-background-position-center"><a class="css" data-link-type="maybe" href="#valdef-background-position-center" id="ref-for-valdef-background-position-center①">center</a></dfn>
<dd>Computes to <span class="css">50%</span> (<span class="css">left 50%</span>) for the
horizontal position if the horizontal position is not otherwise
specified, or <span class="css">50%</span> (<span class="css">top 50%</span>) for the vertical position if
it is.
</dl>
<div class="example" id="example-49046365">
<a class="self-link" href="#example-49046365"></a>
<p>The following <a class="property" data-link-type="propdesc" href="#propdef-background" id="ref-for-propdef-background">background</a> shorthand declarations use keywords
to set <a class="property" data-link-type="propdesc" href="#propdef-background-position" id="ref-for-propdef-background-position⑤">background-position</a> to the stated percentage values.</p>
<pre>body { background: url("banner.jpeg") right top } /* 100% 0% */
body { background: url("banner.jpeg") top center } /* 50% 0% */
body { background: url("banner.jpeg") center } /* 50% 50% */
body { background: url("banner.jpeg") bottom } /* 50% 100% */
</pre>
</div>
<div class="example" id="example-3ceffac0">
<a class="self-link" href="#example-3ceffac0"></a>
<p>In the example below, the (single) image is placed in the lower-right
corner of the viewport. </p>
<pre>body {
background-image: url("logo.png");
background-attachment: fixed;
background-position: 100% 100%;
background-repeat: no-repeat;
}
</pre>
</div>
<div class="example" id="example-d5edaa2c">
<a class="self-link" href="#example-d5edaa2c"></a>
<p>Background positions can also be relative to other corners than the
top left. E.g., the following puts the background image 10px from the
bottom and 3em from the right: </p>
<pre>background-position: right 3em bottom 10px</pre>
</div>
<p>See the section <a href="#layering">“Layering multiple background
images”</a> for how <a class="property" data-link-type="propdesc" href="#propdef-background-position" id="ref-for-propdef-background-position⑥">background-position</a> interacts with
other comma-separated background properties to form each background
image layer. </p>
<h3 class="heading settled" data-level="3.7" id="background-clip"><span class="secno">3.7. </span><span class="content">Painting Area: the <a class="property" data-link-type="propdesc" href="#propdef-background-clip" id="ref-for-propdef-background-clip②">background-clip</a> property</span><span id="the-background-clip"></span><a class="self-link" href="#background-clip"></a></h3>
<table class="propdef">
<tbody>
<tr>
<th>Name:
<td><dfn class="dfn-paneled css" data-dfn-type="property" data-export="" id="propdef-background-clip">background-clip</dfn>
<tr>
<th><a href="#values">Value</a>:
<td><a class="production css" data-link-type="type" href="#typedef-box" id="ref-for-typedef-box"><box></a>#
<tr>
<th>Initial:
<td>border-box
<tr>
<th>Applies to:
<td>all elements
<tr>
<th>Inherited:
<td>no
<tr>
<th>Percentages:
<td>N/A
<tr>
<th>Media:
<td>visual
<tr>
<th>Computed value:
<td>as specified
<tr>
<th>Animatable:
<td>no