Steps to reproduce

1. go to wikipedia on dark mode.
2. pin the appearance menu to the sidebar
3. hide the appearance menu

Expected results

• "The appearance menu has moved..." notification should have white text with a dark background.

Actual results

Environments observed

• Browser version:
• OS version:
• Device model:
• Device language:

Check any additional observations

• Observed on the beta cluster wiki
• Observed on a production wiki
• Observed on Vector desktop skin
• Observed on MinervaNeue responsive skin
• Observed while logged in - https://en.wikipedia.org/wiki/Boundary_Fire_(2017)
• Observed while not logged in (anonymous)

Stack trace