In this WordPress installation I have a problem with my admin menu. If I add clear: left;
to the rules for #adminmenu li.menu-top it appears to be fixed.
WordPress dashboard with borked menu
WordPress dashboard with menu CSS fixed
WordPress admin menu layout problem
I solved the problem. Apparently, Firefox remembers zoom level between sessions. 😳 Zooming out with <Control>+ or <Control>0 fixes it.