Re: [csswg-drafts] [css-conditional] `@supports-condition`, for larger feature queries and named reuse (#12622)

Based on your answers, it must evaluate to false whenever [*consume a block's contents*](https://drafts.csswg.org/css-syntax-3/#consume-a-blocks-contents) get nothing from consuming a rule or a declaration, and forgiving parsing must be disabled.

I have not included examples with `@charset`, `@import`, `@namespace`.

A different but related problem is that `@supports-condition` may be restricted to nested style/grouped rules when nested in a style rule, according to [CSS Nesting](https://drafts.csswg.org/css-nesting-1/#nested-group-rules).

```css
style {
  @supports-condition --name { @font-face {} }
  @supports (--name) {} /* evaluates to false even if @font-face is supported */
}
```

But these are minor problems that can be fixed later and discussed in a separate issue, I guess.

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Received on Wednesday, 5 November 2025 11:02:54 UTC