improved styling of <details> and <summary> elements

[dbaron]

Request for Mozilla Position on an Emerging Web Specification

• Specification title: improved styling of <details> and <summary> elements
• Specification or proposal URL: Not a single spec, but a set of changes initially discussed in Proposal for improvements to <details> styling openui/open-ui#744 and now moved to improve styling of <details>/<summary> elements w3c/csswg-drafts#9879 and Specify the rendering of <details> in more detail. whatwg/html#10265 for the parts that belong in CSS and HTML respectively.
• Explainer URL (if available): https://github.com/dbaron/details-styling
• Proposal author(s) (@-mention GitHub accounts): @dbaron
• Caniuse.com URL (optional): none
• Bugzilla URL (optional): One piece of it is covered by https://bugzilla.mozilla.org/show_bug.cgi?id=1856374 but other bugs are needed for other parts.
• Mozillians who can provide input (optional): @emilio
• WebKit standards-position:

Other information

I realize this is perhaps a little fuzzy, but I think most specifically it's useful to have a position on:

• the set of changes in Specify the rendering of <details> in more detail. whatwg/html#10265
• the addition of the ::details-content pseudo-element.

[martinthomson]

@emilio, I see that you approved the HTML pull request. Does that mean that you think that this is OK? (FWIW, the TAG looked at this as well and I think it's a useful change.)

So, positive?

[emilio]

Yes, positive sgtm