1885509 - Remove UA styles for :is(article, aside, nav, section) h1 (staged rollout)

Status: RESOLVED FIXED

(Core :: Layout, task, P3)

Description

[Simon Pieters [:zcorpan]]

See https://bugzilla.mozilla.org/show_bug.cgi?id=1883896 and https://github.com/whatwg/html/issues/7867#issuecomment-1999318189

If we don't get a lot of bug reports for this change from Nightly users, submit a spec PR and then maybe do a staged rollout.

Comment 1

[Simon Pieters [:zcorpan]]

Chromium has landed a deprecation, which will affect scores in Lighthouse. https://chromium-review.googlesource.com/c/chromium/src/+/6318939

I think we can move forward with a Nimbus experiment now.

Comment 2

[Simon Pieters [:zcorpan]]

Intent to unship: https://groups.google.com/a/mozilla.org/g/dev-platform/c/CzG_pVa7pws/m/Ab3Bwsg2BQAJ

Comment 3

[Simon Pieters [:zcorpan]]

Release Note Request (optional, but appreciated)
[Why is this notable]: Some websites may have different rendering (font-size or margin) for h1 elements for 50% of users of Firefox beta 138 on desktop.
[Affects Firefox for Android]: No for the rollout, but the same change is planned to ship (maybe in 140)
[Suggested wording]: 50% of Firefox beta 138 users will have the change where <h1> always has the same UA style, even in article, aside, nav, section.
[Links (documentation, blog post, etc)]: https://groups.google.com/a/mozilla.org/g/dev-platform/c/CzG_pVa7pws/m/Ab3Bwsg2BQAJ

Comment 4

[Dianna Smith [:diannaS]]

Added to 138 beta release notes
https://www.mozilla.org/en-US/firefox/138.0beta/releasenotes/

Comment 5

[Simon Pieters [:zcorpan]]

Update for release notes:

From April 14, the rollout is 100% of users of Firefox Beta 138 on desktop.

It will be rolled out to 5% of Firefox Release 138, then increase to 10% after 2 weeks.

Comment 6

[Dianna Smith [:diannaS]]

Changed to 100% for Beta, and will address the release wording before go live.

Comment 7

[Simon Pieters [:zcorpan]]

Rollouts have ended, and the change has shipped in 140 (bug 1964922).