Re: [csswg-drafts] [selectors-4] Clarify :lang() behavior when the language range is not a well-formed BCP 47 code (#8720)

> WPT were updated already by Chromium WPT export

I don't think the tests are entirely correct. In particular, https://wpt.live/css/selectors/selectors-4/lang-singleton-subtag-matching.html has tests that expect to match the tags `fr-x` and `zh-x`, but AFAICS according to [BCP47 syntax](https://www.rfc-editor.org/rfc/rfc5646.html#section-2.1) these are ill-formed: the `x` singleton that indicates private-use is _only_ allowed if followed by a further subtag.

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Received on Wednesday, 22 April 2026 16:01:47 UTC