Board Thread:Support Requests - Designing Your Wikia/@comment-4189499-20140711140017/@comment-5454372-20140712123330

Firefox user here. The navbar looks the same as your IE and Chrome screenshots from where I'm standing.

I'd suggest checking your own personal CSS on that wiki as well as here, something may be interfering with it if it's still happening (possibly a line of code with -moz- in it).