Re: [csswg-drafts] [css-conditional-4] Feature detection for descriptors (#2463)

I like the `@supports descriptor()` proposal. However, I'm not sure if it covers the `@property` use-case. The `syntax` descriptor in particular accepts any `<string>` parse time, so simply checking if there's a parse error (like we do in other `@support` cases) won't be enough. Probably each descriptor would need to define how to behave when used in a `@supports descriptor()`.

I also wonder if there are any traps regarding some descriptors depending on other descriptors. For example, the following is hard to evaluate if we don't also know the `syntax`:

```
@supports descriptor(@property, initial-value: 1em) { ... }
```

For syntax `"*"` it's valid, but for e.g. `"<length>"` it's not.


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Received on Thursday, 30 April 2020 15:28:20 UTC