Background selector partially hidden when there are global tabs on a dashboard

[sadpandajoe]

Bug description

When there are global tabs on a dashboard, clicking on the first row to change the background partially hides the background menu text

How to reproduce the bug

1. Create a dashboard
2. Add global tabs to the dashboard
3. Add a chart to the dashboard
4. Click on the cog to open the background menu

Screenshots/recordings

Superset version

4.0.2

Python version

3.9

Node version

16

Browser

Chrome

Additional context

No response

Checklist

• I have searched Superset docs and Slack and didn't find a solution to my problem.
• I have searched the GitHub issue tracker and didn't find a similar bug report.
• I have checked Superset's logs for errors and if I found a relevant Python stacktrace, I included it here as text in the "additional context" section.