Fix checked checkboxes in admin color schemes

[sabernhardt]

[61645] set the checkboxes' check mark and radio buttons' dot to white against the theme's background color.

However, _admin.scss only used the newer syntax for CSS content (see #64350) and did not remove the SVGs that specify the variables.$form-checked color. As a result, color schemes other than Fresh override the white check mark in old browsers.

[sabernhardt]

checkboxes in Modern scheme on the Profile page, using Firefox 115

Removes CSS for the checked states of both checkboxes and radio buttons from _admin.scss. The white color used in all schemes is already defined in forms.css:

input[type="checkbox"]:checked::before {
	content: url("data:image/svg+xml;utf8,%3Csvg%20xmlns%3D%27http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%27%20viewBox%3D%270%200%2020%2020%27%3E%3Cpath%20d%3D%27M14.83%204.89l1.34.94-5.81%208.38H9.02L5.78%209.67l1.34-1.25%202.57%202.4z%27%20fill%3D%27%23ffffff%27%2F%3E%3C%2Fsvg%3E");
	content: url("data:image/svg+xml;utf8,%3Csvg%20xmlns%3D%27http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%27%20viewBox%3D%270%200%2020%2020%27%3E%3Cpath%20d%3D%27M14.83%204.89l1.34.94-5.81%208.38H9.02L5.78%209.67l1.34-1.25%202.57%202.4z%27%20fill%3D%27%23ffffff%27%2F%3E%3C%2Fsvg%3E") / '';
}

Trac 64822

Use of AI Tools: none (by me)

[sabernhardt]

If there is any reason to expect a different rule between core's forms and colors stylesheets, _admin.scss could keep the redundant rulesets like in ​my fork. (I could submit that as a pull request to consider for an alternative option.)

Alternative option: fix the checkbox style in _admin.scss, setting the check mark to white again (even though it is already white in forms.css).

Trac 64822

Use of AI Tools: none (by me)

[joedolson]

I have a strong preference for removing CSS over adding redundancy, and haven't yet been able to think of a good reason to have those colors be different in the stack.

Given that, I'm going to mark this for commit and commit the changes in PR11194. This can easily be changed during RC if we find that there are cases we didn't consider, but removing unneeded CSS is significantly preferable to me.

[ozgursar]

Patch Testing Report

Patch Tested: ​https://github.com/WordPress/wordpress-develop/pull/11198

Environment

• WordPress: 7.0-beta4-61919-src
• PHP: 8.2.29
• Server: nginx/1.29.4
• Database: mysqli (Server: 8.4.7 / Client: mysqlnd 8.2.29)
• Browser: Firefox 115.0
• OS: macOS
• Theme: Twenty Twenty-Five 1.4
• MU Plugins: None activated
• Plugins:
  • Test Reports 1.2.1

Steps taken

1. Use an older browser like Firefox 115
2. Go to Users > Profile
3. Confirm that the white checkmark is not white
4. Apply patch
5. Go to Users > Profile
6. Confirm that the checkmark is white
7. ✅ Patch is solving the problem

Expected result

• We expect to see the which checkmark against the background set in admin color scheme

Screenshots/Screencast with results

Before (Desktop view)

Before (Mobile view)

---

After (Desktop view)

After (Mobile view)

[ozgursar]

@joedolson I accidentally removed the keyword commit while submitting my patch test
Could you add back please?

[joedolson]

In 61940:

Admin: Fix checked input state in older browsers.

Remove duplicate CSS setting the checked state for checkbox and radio inputs from _admin.scss. The duplicate selectors overrode the white checkmark in older browsers, impacting alternate color schemes.

Props sabernhardt, joedolson.
Fixes #64822.

Committed in r61940

#11194 was committed in r61940