At certain screen resolutions, the navigation bar at the top of local file description pages does not properly collapse, and instead -- without the user doing anything -- continously switches between collapsing and expanding the last tab.

Steps to reproduce:

1. Go to https://de.wikipedia.org/wiki/Datei:Otzenrathpano2.jpg?uselang=de using Firefox or Chrome. Note that in my case, I could only reproduce this issue when I was logged out, but that might be just me.
2. Zoom in until the described behavior occurs

I've attached a screencast illustrating this behavior setting in as the zoom level is increased. (The image depicted is titled Otzenrathpano2.jpg, authored by Bodoklecksel and licensed under the GNU Free Documentation License, Version 1.2.)