Description

In the Guide component, the close button becomes invisible when hovered. It changes to white, blending into the white background.

Step-by-step reproduction instructions

1. Visit https://wordpress.github.io/gutenberg/?path=/docs/components-guide--docs
2. Click Open Guide Button
3. Hover over the Close (×) button in the top-right corner
4. Observe: The button disappears because it becomes white

Screenshots, screen recording, code snippet

Default State

Hover State

Environment info

WP Version: 6.8.3
Gutenberg Version: 22.1.0-rc.1
Theme: Twenty Twenty-Five
Browser: Chrome, Brave
OS: Windows 11

Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes

Please confirm which theme type you used for testing.

• Block
• Classic
• Hybrid (e.g. classic with theme.json)
• Not sure