Correct bg color of disabled indeterminate checkbox

[mperrotti]

Closes https://github.com/github/primer/issues/5273

Before	After

Changelog

New

Changed

• Background of indeterminate checkbox is now "greyed out" when disabled

Removed

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; if selected, include a brief description as to why

Testing & Reviewing

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github (Learn more about how to run integration tests)

[changeset-bot]

🦋 Changeset detected

Latest commit: ca93370

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@primer/react	Patch
@primer/styled-react	Patch

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[Copilot]

Pull Request Overview

This PR corrects the background color of disabled indeterminate checkboxes by reorganizing CSS selector order to ensure proper inheritance. The disabled styling was not being applied to indeterminate checkboxes due to CSS specificity conflicts.

• Moved general :disabled styles after the :checked selector block
• Ensures disabled indeterminate checkboxes inherit the "greyed out" appearance consistently

[github-actions]

Uh oh! @mperrotti, at least one image you shared is missing helpful alt text. Check your pull request body to fix the following violations:

• Images should have meaningful alternative text (alt text) at line 7
• Images should have meaningful alternative text (alt text) at line 7
• Images should have meaningful alternative text (alt text) at line 7
• Images should have meaningful alternative text (alt text) at line 7

Alt text is an invisible description that helps screen readers describe images to blind or low-vision users. If you are using markdown to display images, add your alt text inside the brackets of the markdown image.

Learn more about alt text at Basic writing and formatting syntax: images on GitHub Docs.

🤖 Beep boop! This comment was added automatically by github/accessibility-alt-text-bot.

[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github depends on. If you are GitHub staff, we recommend testing these changes with github/github using the integration workflow. Thanks!

[francinelucca]

wondering if this is worth sneaking into some VRT story 👀

[mperrotti]

wondering if this is worth sneaking into some VRT story 👀

@francinelucca - I think this covers it :)