How to feature detect support for new at-rule?

Matthias Zöchling wrote on August 5, 2026 at 06:53 Nifty! @supports at-rule(@supports) { /* ✅ The browser supports `@supports at-rule(…)` */ } As seen in “Detect at-rule support in CSS with @supports at-rule(@keyword)” by @bram.us Nicolas Chevobbe wrote on August 5, 2026 at 07:46 In reply to: @CSSence@mas.to. eh, this was just sent“Intent to Prototype: CSS at-rule() function for @supports”