Web features explorer - at-rule()

Web features explorer

The at-rule() function, when used with @supports, checks if a CSS at-rule is supported. For example @supports at-rule(@starting-style) checks if the @starting-style at-rule is supported.

Browser support

Chrome 148 Released on 2026-05-05
Chrome Android 148 Released on 2026-05-05
Edge 148 Released on 2026-05-07
Firefox 157 Released on 2026-09-29
Firefox for Android 157 Released on 2026-09-29
Safari Not supported Position: support
Safari on iOS Not supported Position: support

Baseline availability blocked since September 2026 by Safari (1 months)

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MDN documentation

No MDN documentation found. You can search for the feature on MDN. If you believe that MDN has no documentation about this feature, you can open an issue on MDN's GitHub repository.

Specifications

CSS Conditional Rules Module Level 5 (#typedef-supports-at-rule-fn), from Cascading Style Sheets (CSS) Working Group (W3C).

Web Platform Tests (WPT)

View the latest WPT test results for this feature

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