Re: [csswg-drafts] [css-conditional] Is the `at-rule` function all that necessary? (#12997)

Yup, what you're missing is our general decision to make any of the boolean grammars conform to "particles are always parenthesized or functions", so we can actually define `<general-enclosed>` (the catch-all error term in the `<boolean>` grammar) in a way that lets us parse in a forwards-compatible fashion. If the tests could be *anything*, we'd have no way to know where `<general-enclosed>` should end, so we'd have to fail parsing the entire tree when we encountered anything unknown.

See <https://www.w3.org/TR/css-values-5/#typedef-boolean-expr> and <https://www.w3.org/TR/mediaqueries-5/#typedef-general-enclosed>

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Received on Tuesday, 21 October 2025 17:14:23 UTC