Intent to Prototype:
Summary: The CSS Selectors Level 4 spec enhances the CSS :lang()
pseudo-class to provide authors with more flexible matching behavior,
based on BCP47 "Tags for Identifying Languages" and RFC4647 "Matching of
For example, it becomes possible to use a selector such as :lang("*-CH")
to match content tagged as any language with a Swiss region subtag,
instead of having to write separate selectors for each of de-CH, fr-CH,
Standards Body: CSS Working Group
Platform coverage: All platforms/contexts
Preference: Not planning to put this behind a pref; it will simply be an
enhancement of the capabilities of an existing feature.
DevTools bug: n/a
Link to standards-positions discussion:
Blink: Intent to Ship:
WebKit: Shipped (since around 2015, I believe), though I have noted some
spec-conformance issues with their implementation.
web-platform-tests: Proposing to add some WPT tests in the Gecko bug;
Blink implementers are also working on adding tests.
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Intent to Ship:
As of Firefox 114 (if all goes well), I intend to turn CSS Selectors 4
:lang() matching on by default for all platforms. I expect this to land
directly without being gated on a preference.
Status in other browsers is WebKit: shipping; Blink: Intent to Ship (see
Bug to turn on by default: