Add support for the 'font-language-override' CSS property

[seanand-dev]

WebKittens

No response

Title of the proposal

Add support for the 'font-language-override' CSS property

URL to the spec

https://www.w3.org/TR/css-fonts-4/#font-language-override-prop

URL to the spec's repository

No response

Issue Tracker URL

No response

Explainer URL

No response

TAG Design Review URL

No response

Mozilla standards-positions issue URL

No response

WebKit Bugzilla URL

https://bugs.webkit.org/show_bug.cgi?id=150081

Radar URL

No response

Description

Add support for the 'font-language-override' CSS
property, which allows authors to the system language used for glyph
substitution at the CSS level by specifying a four-character OpenType
language tag.

[annevk]

w3c/csswg-drafts#5484 lists some issues we had with this feature in the past. It made me wonder whether there is a well-defined algorithm from a BCP47 language to the four-letter variant that OpenType supports?

It also seems like an extremely confusing web platform API to have something called "language" but it not taking a BCP47 language. How do we expect people to hold this correctly?