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The CSSSupportsRule interface describes an object representing a single CSS @supports at-rule. It implements the CSSConditionRule interface, and therefore the CSSRule and CSSGroupingRule interfaces with a type value of 12 (CSSRule.SUPPORTS_RULE).


The syntax is described using the WebIDL format.

interface CSSSupportsRule : CSSConditionRule {


As a CSSConditionRule and therefore a CSSRule and a CSSGroupingRule, CSSSupportsRule also implements the properties of these interfaces. It has no specific properties.


As a CSSConditionRule and therefore a CSSRuleand a CSSGroupingRule, CSSSupportsRule also implements the methods of that interface. It has no specific methods.


Specification Status Comment
CSS Conditional Rules Module Level 3
The definition of 'CSSSupportsRule' in that specification.
Candidate Recommendation Initial definition

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari (WebKit)
Basic support Not supported 17 (17)[1] Not supported 12.10 Not supported
Feature Android Firefox Mobile (Gecko) IE Phone Opera Mobile Safari Mobile
Basic support Not supported 17.0 (17)[1] Not supported Not supported Not supported

[1] As prefixing this at-rule has no sense, the CSSSupportsRule is only supported if the user enables it by setting the config value layout.css.supports-rule.enable to true.

From Firefox 17 to Firefox 19 included, CSSSupportsRule derived directly from CSSRule and the methods and properties now defined at the CSSConditionRule level where defined in CSSSupportsRule. The draft specification changed and Firefox 20 was updated.

See also

Document Tags and Contributors

 Contributors to this page: fscholz, Sebastianz, teoli, kscarfone, Sheppy, webinista
 Last updated by: fscholz,