3.0: Grouped Piece Types in Expand to Fill Width of Dropdown

[joeinnes]

PLEASE NOTE: make sure the bug exists in the latest patch level of your major version of Apostrophe. For instance, if you are running a 2.x version of Apostrophe, you should use the latest in that major version to confirm the bug.

To Reproduce

Step by step instructions to reproduce the behavior:

1. Add Grouped Piece Types to the menu bar
2. Click on a group heading (especially if a piece type has a longer name)
3. See error

Expected behavior

Other top level menu items should not move

Describe the bug

Other items move to accommodate the dropdown

Details

Version of Node.js: PLEASE NOTE: Only stable LTS versions (10.x and 12.x) are fully supported but we will do our best with newer versions. v15.2.0 (although bug is in frontend)

Server Operating System: The server (which might be your dev laptop) on which Apostrophe is running. Linux? MacOS X? Windows? Is Docker involved? macOS Big Sur. I am using Docker to host MongoDB, but I don't think that's a contributing factor.

Additional context:

Add any other context about the problem here. If the problem is specific to a browser, OS or mobile device, specify which. Only tested on Safari

Screenshots If applicable, add screenshots to help explain your problem.