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conformance · v148

v148 · at-rule-css-feature-detection — conformance probe

5 assertions drawn from the spec. Each is a single contract the spec text makes. Pass/fail reflects what this browser executed; blocked means the contract was not run because it needs user mediation, hardware, or another unavailable precondition. Open the page in Chrome stable / canary / Firefox / Safari to compare.

browser: spec: https://drafts.csswg.org/css-conditional-5/#support-definition-at-rules chromestatus: #5110744177836032 generated 2026-06-01T08:14:38Z by conformance-author-v1-subagent
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pass
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id contract kind verdict detail
supports-at-rule-function CSS.supports parses the at-rule() condition function. spec ↗ script
supports-at-rule-known at-rule(@font-face) reports support for a universally supported at-rule. spec ↗ script
supports-at-rule-unknown-false at-rule(@definitely-not-an-at-rule) returns false rather than throwing. spec ↗ script
supports-rule-at-rule-in-stylesheet @supports (at-rule(@container)) wraps rules conditionally. spec ↗ script
supports-at-rule-descriptor at-rule() accepts a descriptor argument like at-rule(@font-face; font-display). spec ↗ script