Add experimental h1 UA styles removal

[pepelsbey]

Description

• Adds experimental h1 UA styles removal info into Firefox 125 release notes and to the Experimental features page
• Fixes headings levels for two other experimental features: they seem to be not grouped.

Motivation

Upcoming Firefox 125 release.

Additional details

• Bugzilla: Remove UA styles for :is(article, aside, nav, section) h1 (Nightly only)

Related issues and pull requests

• [Nightly][CSS] Remove UA styles for :is(article, aside, nav, section) h1 #32746

[github-actions]

Preview URLs

• /en-US/docs/Mozilla/Firefox/Experimental_features
• /en-US/docs/Mozilla/Firefox/Releases/125

External URLs (5)

URL: /en-US/docs/Mozilla/Firefox/Experimental_features
Title: Experimental features in Firefox

• https://bugzil.la/1855763 (3 times) (Note! This may be a new URL 👀)
• https://bugzil.la/1883896 (1 time) (Note! This may be a new URL 👀)
• replace current outline algorithm with one based on heading levels whatwg/html#7829 (1 time) (Note! This may be a new URL 👀)

---

URL: /en-US/docs/Mozilla/Firefox/Releases/125
Title: Firefox 125 for developers

• https://bugzil.la/1883896 (1 time) (Note! This may be a new URL 👀)
• replace current outline algorithm with one based on heading levels whatwg/html#7829 (1 time) (Note! This may be a new URL 👀)

(comment last updated: 2024-04-16 10:11:19)

[dipikabh]

Thanks, Vadim!
I have a few questions and suggestions.

[dipikabh]

It's close and getting better, thanks for the clarifications!

[dipikabh]

Thanks for the updates, @pepelsbey! Approving.

Note:

• @zcorpan's comment needs to be fixed because of the table header change back to the previous one based on my suggestion but pref behavior is reverse. Sorry for the mix up
• Text changes need to be replicated to firefox/releases/125/index.md file as well.

[github-actions]

This pull request has merge conflicts that must be resolved before it can be merged.

[pepelsbey]

zcorpan's comment needs to be fixed
text changes need to be replicated to firefox/releases/125/index.md file as well.

Done and done. Thank you both!