Limited Availability CSS

at-rule()

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.

Baseline Status: This feature is currently Limited (not yet Baseline). Latest engine implementation shipped on Sep 29, 2026.

Desktop Browser Engine Support

Google Chrome

148

Supported

Mozilla Firefox

157

Supported

Apple Safari

—

Unsupported

Microsoft Edge

148

Supported

Mobile Browser Engine Support

Chrome Android

148

Firefox Android

157

Safari iOS

—

Specifications and References

Specification ↗ Feature XML ↗

MDN Browser Compat Data Keys:

css.at-rules.supports.at-rule ↗