Plugins/Themes: Filter component doesn't use new colors

[ocean90]

See attached screenshots for the old colors used in the .wp-filter component. The filter is used on the screen for adding new plugins/themes.

Trac ticket:

## Use of AI Tools

[noruzzaman]

This patch updates the background color of the feature filter button in the Themes screen. The current border color does not match the updated background, so it should also be adjusted to maintain visual consistency.

Trac ticket: https://core.trac.wordpress.org/ticket/64788

## Summary

The .wp-filter component used on the Add Plugins and Add Themes screens
is still using legacy hardcoded color values instead of the new admin
color variables introduced as part of the admin reskin.

This causes visual inconsistencies with the updated admin color system.

## Changes

• Replaced hardcoded color values with the appropriate CSS custom properties:
  • --wp-admin-theme-color
  • --wp-admin-theme-color-darker-10
  • --wp-admin-border-color
• Ensured hover, focus, and active states use the new design tokens.
• No visual changes outside of the filter component.

Thanks for the PR.
I noticed only var(--wp-admin-theme-color) is used, while the description mentions other variables as well. Could you clarify why?

Also, a similar fix already exists in PR ​https://github.com/WordPress/wordpress-develop/pull/11153
Is there a reason for opening another PR?

@huzaifaalmesbah You’re right — the patch only uses var(--wp-admin-theme-color). The PR description was incorrect in mentioning --wp-admin-theme-color-darker-10 and --wp-admin-border-color. I’ll update the description.

I wasn’t aware of PR #11153 when I opened this.

[SergeyBiryukov]

In 61832:

Admin Reskin: Correct color scheme for plugin and theme filters.

Props ocean90, niravsherasiya7707, noruzzaman, manishxdp, huzaifaalmesbah, SergeyBiryukov.
Fixes #64788.