---
title: CSSRule
slug: Web/API/CSSRule
tags:
  - CSSOM
translation_of: Web/API/CSSRule
---
<div>{{APIRef("CSSOM")}}</div>

<p>An object implementing the <strong><code>CSSRule</code></strong> DOM interface represents a single CSS at-rule. References to a <code>CSSRule</code>-implementing object may be obtained by looking at a <a href="/en-US/docs/Web/API/CSSStyleSheet">CSS style sheet's</a> {{domxref("CSSStyleSheet","cssRules")}} list.</p>

<p>There are several kinds of rules. The <code>CSSRule</code> interface specifies the properties common to all rules, while properties unique to specific rule types are specified in the more specialized interfaces for those rules' respective types.</p>

<h2 id="Properties" name="Properties">Syntax</h2>

<p>The syntax is described using the <a href="http://dev.w3.org/2006/webapi/WebIDL/">WebIDL</a> format.</p>

<pre>interface CSSRule {
    const unsigned short STYLE_RULE = 1;
    const unsigned short CHARSET_RULE = 2;
    const unsigned short IMPORT_RULE = 3;
    const unsigned short MEDIA_RULE = 4;
    const unsigned short FONT_FACE_RULE = 5;
    const unsigned short PAGE_RULE = 6;
    const unsigned short KEYFRAMES_RULE = 7;
    const unsigned short KEYFRAME_RULE = 8;
    const unsigned short NAMESPACE_RULE = 10;
    const unsigned short COUNTER_STYLE_RULE = 11;
    const unsigned short SUPPORTS_RULE = 12;
    const unsigned short DOCUMENT_RULE = 13;
    const unsigned short FONT_FEATURE_VALUES_RULE = 14;
    const unsigned short VIEWPORT_RULE = 15;
    const unsigned short REGION_STYLE_RULE = 16;
    readonly attribute unsigned short type;
    attribute DOMString cssText;
    readonly attribute CSSRule? parentRule;
    readonly attribute CSSStyleSheet? parentStyleSheet;
};</pre>

<h2 id="Properties_common_to_all_CSSRule_instances">Properties common to all CSSRule instances</h2>

<dl>
 <dt id="cssText">{{domxref("CSSRule.cssText")}}</dt>
 <dd>Represents the textual representation of the rule, e.g. <code>"h1,h2 { font-size: 16pt }"</code></dd>
 <dt id="parentRule">{{domxref("CSSRule.parentRule")}} {{readonlyinline}}</dt>
 <dd>Returns the containing rule, otherwise <code>null</code>. E.g. if this rule is a style rule inside an {{cssxref("@media")}} block, the parent rule would be that {{domxref("CSSMediaRule")}}.</dd>
 <dt id="parentStyleSheet">{{domxref("CSSRule.parentStyleSheet")}} {{readonlyinline}}</dt>
 <dd>Returns the {{domxref("CSSStyleSheet")}} object for the style sheet that contains this rule</dd>
 <dt id="type">{{domxref("CSSRule.type")}} {{readonlyinline}}</dt>
 <dd>One of the {{anch("Type constants")}} indicating the type of CSS rule.</dd>
</dl>

<h2 id="CSSRule" name="CSSRule">Constants</h2>

<h3 id="Type_constants">Type constants</h3>

<p>The <code>CSSRule</code> interface specifies integer constants that can be used in conjunction with a <code>CSSRule</code>'s {{domxref("cssRule/type","type")}} property to discern the rule type (and therefore, which specialized interface it implements). The relationships between these constants and the interfaces are:</p>

<table class="standard-table">
 <tbody>
  <tr>
   <th>Type</th>
   <th>Value</th>
   <th>Rule-specific interface</th>
  </tr>
  <tr>
   <td><code>CSSRule.STYLE_RULE</code></td>
   <td style="text-align: center;"><code>1</code></td>
   <td>{{domxref("CSSStyleRule")}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.MEDIA_RULE</code></td>
   <td style="text-align: center;"><code>4</code></td>
   <td>{{domxref("CSSMediaRule")}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.FONT_FACE_RULE</code></td>
   <td style="text-align: center;"><code>5</code></td>
   <td>{{domxref("CSSFontFaceRule")}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.PAGE_RULE</code></td>
   <td style="text-align: center;"><code>6</code></td>
   <td>{{domxref("CSSPageRule")}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.IMPORT_RULE</code></td>
   <td style="text-align: center;"><code>3</code></td>
   <td>{{domxref("CSSImportRule")}} : <a href="http://mxr.mozilla.org/mozilla-central/source/dom/interfaces/css/nsIDOMCSSImportRule.idl#9">IDL: nsIDOMCSSImportRule</a></td>
  </tr>
  <tr>
   <td><code>CSSRule.CHARSET_RULE</code></td>
   <td style="text-align: center;"><code>2</code></td>
   <td>{{domxref("CSSCharsetRule")}} {{obsolete_inline}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.UNKNOWN_RULE</code></td>
   <td style="text-align: center;"><code>0</code></td>
   <td>{{domxref("CSSUnknownRule")}}{{obsolete_inline}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.KEYFRAMES_RULE</code></td>
   <td style="text-align: center;"><code>7</code></td>
   <td>{{domxref("CSSKeyframesRule")}} [1] {{experimental_inline}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.KEYFRAME_RULE</code></td>
   <td style="text-align: center;"><code>8</code></td>
   <td>{{domxref("CSSKeyframeRule")}} [1] {{experimental_inline}}</td>
  </tr>
  <tr>
   <td><em>Reserved for future use</em></td>
   <td style="text-align: center;"><code>9</code></td>
   <td>Should be used to define color profiles in the future</td>
  </tr>
  <tr>
   <td><code>CSSRule.NAMESPACE_RULE</code></td>
   <td style="text-align: center;"><code>10</code></td>
   <td>{{domxref("CSSNamespaceRule")}} {{experimental_inline}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.COUNTER_STYLE_RULE</code></td>
   <td style="text-align: center;"><code>11</code></td>
   <td>{{domxref("CSSCounterStyleRule")}} {{experimental_inline}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.SUPPORTS_RULE</code></td>
   <td style="text-align: center;"><code>12</code></td>
   <td>{{domxref("CSSSupportsRule")}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.DOCUMENT_RULE</code></td>
   <td style="text-align: center;"><code>13</code></td>
   <td>{{domxref("CSSDocumentRule")}} {{experimental_inline}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.FONT_FEATURE_VALUES_RULE</code></td>
   <td style="text-align: center;"><code>14</code></td>
   <td>{{domxref("CSSFontFeatureValuesRule")}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.VIEWPORT_RULE</code></td>
   <td style="text-align: center;"><code>15</code></td>
   <td>{{domxref("CSSViewportRule")}} {{experimental_inline}}</td>
  </tr>
  <tr>
   <td><code>CSSRule.REGION_STYLE_RULE</code></td>
   <td style="text-align: center;"><code>16</code></td>
   <td>{{domxref("CSSRegionStyleRule")}} {{experimental_inline}}</td>
  </tr>
 </tbody>
</table>

<p>An up-to-date informal list of constants can be found on the <a href="http://wiki.csswg.org/spec/cssom-constants">CSSWG Wiki</a>.</p>

<p>[1] On Gecko, before Firefox 19, the keyframe-related constants existed only in their prefixed version: <code>CSSRule.MOZ_KEYFRAMES_RULE</code> and <code>CSSRule.MOZ_KEYFRAME_RULE.</code> From Firefox 20 onwards, both versions are available. The prefixed version will be removed in the future.</p>

<h2 id="Specification" name="Specification">Specifications</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{SpecName('CSSOM', '#css-rules', 'CSSRule')}}</td>
   <td>{{Spec2('CSSOM')}}</td>
   <td>Obsoleted values <code>CHARSET_RULE</code> and <code>UNKNOWN_RULE</code>. Added value <code>NAMESPACE_RULE</code>.</td>
  </tr>
  <tr>
   <td>{{SpecName("CSS3 Animations",'#cssrule', 'CSSRule')}}</td>
   <td>{{Spec2('CSS3 Animations')}}</td>
   <td>Added values <code>KEYFRAMES_RULE</code> and <code>KEYFRAME_RULE</code>.</td>
  </tr>
  <tr>
   <td>{{SpecName('CSS3 Fonts', '#om-fontfeaturevalues', 'CSSRule')}}</td>
   <td>{{Spec2('CSS3 Fonts')}}</td>
   <td>Added value <code>FONT_FEATURE_VALUES_RULE</code>.</td>
  </tr>
  <tr>
   <td>{{SpecName("CSS3 Counter Styles", "#extentions-to-cssrule-interface", 'CSSRule')}}</td>
   <td>{{Spec2("CSS3 Counter Styles")}}</td>
   <td>Added value <code>COUNTER_STYLE_RULE</code>.</td>
  </tr>
  <tr>
   <td>{{SpecName("CSS3 Conditional", '#extentions-to-cssrule-interface', 'CSSRule')}}</td>
   <td>{{Spec2('CSS3 Conditional')}}</td>
   <td>Added value <code>SUPPORTS_RULE</code>. (<code>DOCUMENT_RULE</code> has been pushed to CSS Conditional Rules Level 4)</td>
  </tr>
  <tr>
   <td>{{SpecName('DOM2 Style', 'css.html#CSS-CSSRule', 'CSSRule')}}</td>
   <td>{{Spec2('DOM2 Style')}}</td>
   <td>Initial definition.</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>

<p>To get browser compatibility information about the different type constant value, please consult the compatibility table of the associated interface.</p>

<div>{{CompatibilityTable}}</div>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari (WebKit)</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>9</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>IE Phone</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
   <td>{{CompatVersionUnknown}}</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="See_also">See also</h2>

<ul>
 <li><a href="/en-US/docs/Web/Guide/DOM/Using_dynamic_styling_information">Using dynamic styling information</a></li>
</ul>