Long names cause avatar to disappear from Drawer and the 'Close the drawer' button to be shifted out of view

Steps to reproduce

1. Create/Register an user with a long First/Last Name such as: Christopher Wolfeschlegelsteinhausenbergerdorff
2. Login with the user, go to its profile page
3. Set a custom avatar
4. (Refresh the page) Click on 'Drawer' button

Expected results

On Drawer, all elements are in their place and visible.

Actual results

The avatar is missing and the 'Close the drawer' button is shifted to the right side, out of view.

The missing avatar doesn't reproduce on XWiki 15.9 or 14.10.20 (the 'Close the drawer' button was not yet present there).