Wow, I hadn't realized the CSS revert-rule keyword (a feature I originally proposed, albeit with a different syntax) is now Baseline, as of Sep 14! 😍 Only 2y4m from initial proposal to Baseline. 1y8m if you count from the WG resolution! Full timeline: https://lea.verou.me/specs/#revert-rule This allows creating declarations with variables etc that disappear entirely when invalid instead of becoming IACVT, paving the way for real block-level conditionals.