Firefox 54.0.1 both 32-bit and 64-bit both Windows and Linux
Hover the mouse over the topmost notifications bell, and the black box with the Notifications caption in white letters completely covers the bell. NBD if one could click anywhere on the caption to open the Notifications drop-down, but that’s not the case. Still need to click where the bell is even though it’s completely hidden.
Same caption placement with Edge, though clicking anywhere in the caption in Edge does display the Notifications drop-down.
Going out of your way to make this site unusable with Firefox.