Seems extremely unlikely.

Unlikely, but also quite unfortunate. I'd certainly support someone investigating this.

cc @whatwg/css

The hgroup special styling could probably be removed since hgroup usage is a lot lower than the sectioning elements, and multiple headings in hgroup is non-conforming with #7829. And it's not implemented in any of Gecko, Chromium, WebKit!

Demo:
https://h1-ua-style.glitch.me/

Maybe it's possible to remove the other rules also; author CSS to set the font-size was needed to get consistent style in older browsers (in particular IE8). But this would need some research.

h2-h5 in hgroup styling removed in #7886

Adding agenda+ to check interest in adding a use counter for h1 with a sectioning element ancestor and no Author Origin style for font-size.

We didn't get to this issue in the triage meeting today. Optimistically tagging @mfreed7 :)

I think the Chromium use counter has some amount of false positives because some sites have a flash of unstyled content (due to forcing layout or loading CSS async). See GoogleChrome/lighthouse#16404 (comment)

I think the Chromium use counter has some amount of false positives because some sites have a flash of unstyled content (due to forcing layout or loading CSS async). See GoogleChrome/lighthouse#16404 (comment)

Thanks for the link - I hadn't seen that bug report. (Makes me happy that the deprecation->Lighthouse->developer path is working!) At first I was thinking about how to avoid providing the deprecation message in that FOUC case, but I think maybe the counter/message is working as expected. I agree that it likely means the counter is likely a bit higher than it should be, but maybe it's ok given the state of this removal?

I agree that it likely means the counter is likely a bit higher than it should be, but maybe it's ok given the state of this removal?

Yeah, no need to tweak the use counter IMO.

Status update: still no broken site reports. Rollout is now active for 10% of release.

Status update: still no reported regressions. I'm calling success on the rollout experiment. When 139 is released, I plan to increase the rollout on desktop to 100%. The pref flip will ride the trains for 140.

Firefox 140 shipped today!

Firefox 140 shipped today!

Congrats! I'm sure you will, but just to be sure: can you please check in one more time when you think this change "stuck" in Firefox and you're sure it'll stay landed? At that point, I'll request shipment of the change in Blink.

Firefox updated the WPT for this ( web-platform-tests/wpt#53658 ) claiming that this part of the UA stylesheet has been removed when it hasn't? cc: @emilio

Ah, you're right, sorry! I think I glanced at https://html.spec.whatwg.org/multipage/rendering.html#sections-and-headings and didn't see :is(..) and assumed it was gone (but it's using x instead, of course :'/).

So I guess at this point we can revert my change (happy to do that) or merge #11102. Both Firefox 139 and 140 have shipped with it at 100% with no regressions reported.

@domenic / @annevk / @mfreed7: Slight preference to merge #11102, but let me know either way?

I think per discussions at #11102 (comment) we've reached the threshold for merging the spec PR, so let's do that within the next couple of days.

@domenic / @annevk / @mfreed7: Slight preference to merge #11102, but let me know either way?

Definitely let's merge #11102 - it feels like this change has sailed. (Or has ridden the trains?) I'll get started with the process to disable on Chromium.

Definitely let's merge #11102 - it feels like this change has sailed. (Or has ridden the trains?) I'll get started with the process to disable on Chromium.

The special rules will be disabled in Chromium as of M140.