Inline H3 header style is visually stronger than the page's H1 (admin, light theme).

[Natalia Bidart]

Following the review of ​PR 18308 (which fixes #35558 and a fix landed in e510bb1ab1fb22837c169e0459b81cf388b6d8d2), it was noticed that since the inline H3 header was set to --body-loud-color, in the light theme this color (black) is stronger than the page's H1, which is --body-quiet-color (#666, dark-ish gray).

The page's H1 should be visually stronger than the H2 and H3 headings, so I'm proposing to:

1. Have the table headers for required fields use --body-fg (#333), instead of black, to match what every other required form label uses, and to visually show a difference between the inline H3 and its content (this is what motivated the changes in #35558).
2. Have the page's H1 use --body-loud-color to ensure this header is visually stronger than any other heading in the page.

PR coming up shortly.

[Sarah Boyce]

Thank you for following up
Unfortunately this would require an update to almost all images in docs/ref/contrib/admin/_images and docs/intro/_images

[nessita <124304+nessita@…>]

In 6e66c77:

Fixed #35645, Refs #35558 -- Added "medium" color in the admin CSS to improve accessibility of headings.

[Natalia <124304+nessita@…>]

In 2c4f0c06:

[5.1.x] Fixed #35645, Refs #35558 -- Added "medium" color in the admin CSS to improve accessibility of headings.

Backport of 6e66c77089fa5498066d2aa593979e4f76f5bedc from main.