This change has now rolled out to 138 release channel (5% the first 2 weeks, 10% the past week), with 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 <https://bugzilla.mozilla.org/show_bug.cgi?id=1964922>.
On Mon, Apr 14, 2025 at 4:38 PM Simon Pieters <[email protected]> wrote: > This change has been rolled out to 50% of beta 138 for the past two weeks. > No reported regressions so far due to this change. > > I have published an article on the MDN Blog > <https://developer.mozilla.org/en-US/blog/h1-element-styles/> which > received some comments on Hacker News > <https://news.ycombinator.com/item?id=43649853>. After taking the > feedback into consideration, the rollout plan is adjusted slightly: > > - Increase the rollout on 138 beta to 100% (asap), so that web > developers who test in beta have a chance to see the change before it > reaches users on release. > - Only roll out to 10% of users on release, instead of 50%. This > should be sufficient to make a decision to ship. > > cheers, > > On Mon, Mar 24, 2025 at 9:57 PM Simon Pieters <[email protected]> wrote: > >> Hi, >> >> As of March 31 I intend to start a rollout of 50% of Beta 138 to >> remove UA styles for h1 in article, aside, nav, section on desktop. We will >> monitor web compat reports to evaluate impact. If it goes well, the plan is >> to roll out to 5% of Release 138 and then increase to 50%, and if it goes >> well, increase to 100% and let the change ride the trains for all platforms. >> >> Status in other browsers is that they are interested in following our >> lead (1 >> <https://github.com/whatwg/html/issues/7867#issuecomment-2125552252>, 2 >> <https://github.com/whatwg/html/issues/7867#issuecomment-2124317504>). >> Chromium has also deprecated >> <https://issues.chromium.org/issues/394111284> this, which makes the >> issue surface for web developers in Chromium's console as well as impacting >> the score in Lighthouse >> <https://github.com/whatwg/html/issues/7867#issuecomment-2711538791>. >> >> *Bug to remove*: https://bugzilla.mozilla.org/show_bug.cgi?id=1885509 >> >> *Spec issue*: https://github.com/whatwg/html/issues/7867 >> >> *Rollout for Beta*: >> https://experimenter.services.mozilla.com/nimbus/remove-ua-styles-for-h1-headings/summary >> >> *Rollout for Release*: >> https://experimenter.services.mozilla.com/nimbus/remove-ua-styles-for-h1-headings-release/summary >> >> *Pref*: layout.css.h1-in-section-ua-styles.enabled (false means the UA >> styles are removed) >> >> *Compat analysis*: >> >> - March 2024: >> https://github.com/whatwg/html/issues/7867#issuecomment-1977647444 >> - January 2025: >> https://github.com/whatwg/html/issues/7867#issuecomment-2595987424 >> >> We have a warning in the devtools console since 136 when a page has a h1 >> in article, aside, nav, or section, and no author-origin font-size or >> margins specified. The pref has been false in Nightly since March 2024, >> with only one web compat issue >> <https://bugzilla.mozilla.org/show_bug.cgi?id=1886480> reported (the >> site was fixed). >> >> Rationale and context for this change: >> >> - h1 was specified to have automatic heading level based on the >> number of ancestor sections (or aside, article, nav). >> - The default rendering was specified to (roughly) match, such that >> <section><h1> would have the same font-size and margin as h2 >> - The default rendering was implemented in browsers, but not the >> heading level in the accessibility tree. >> - Websites started to use sectioning elements, but didn't expect >> automatic heading levels. It was not possible for browsers to change that >> without breaking user expectations. >> - The automatic heading level (a.k.a. the outline algorithm) was >> dropped from the spec, but the default UA stylesheet remained. This is >> what >> we're trying to remove now. >> >> Advice for web developers: >> https://developer.mozilla.org/en-US/docs/Web/HTML/Element/Heading_Elements#specifying_a_uniform_font_size_for_h1 >> >> cheers, >> -- >> Simon Pieters >> https://www.mozilla.com/ >> > > > -- > Simon Pieters > https://www.mozilla.com/ > -- Simon Pieters https://www.mozilla.com/ -- You received this message because you are subscribed to the Google Groups "[email protected]" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/a/mozilla.org/d/msgid/dev-platform/CAC7mYC7O1UaKLdmhzZymodvthetgZJBq%3DM7tT6V_SadapbyvcA%40mail.gmail.com.
