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

  > We should do the same thing we resolved on for custom media queries

What you resolved on does not seem very explicit. :worried:

Given the CSS below, what should be the computed `color` of `div` when the media width is greater than `500px` at parse time? and if it becomes lower than `500px`?

```css
div {
  @supports-condition --name {/*everything is supported*/}
  @media (width > 500px) {
    @supports-condition --name { unknown: value; }
  }
  color: red;
  @supports --name {
    color: green;
  }
  @supports-condition --name {} /* always ignored? */
}
```

In any case, I expect that `@supports-condition` with the same name will not be dropped, like other at-rules registering named things.

---

It would be great to clarify this:

  > Anything inside the block is evaluated to test whether the user agent supports the features used.

Should `CSS.supports()` return true when receiving these values?

  - `style { /* comment */ } })`
  - `style { oups; } })`
  - `style { @media --oups {} } })`
  - `style { @media (oups) {} } })`
  - `style { color: green; color: green; } })`

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Received on Tuesday, 4 November 2025 05:30:50 UTC