That makes sense, I probably should have given you a link to see it not working, my bad! Here it is – http://zwiv.net
It’s at the very top and as you can see, there’s no background.
About .dropdown being generic, I thought about that but after searching through the MyBB CSS I couldn’t find anything, I’ll try changing it to something new and see if it works.
EDIT: I changed it to a different name but got the same result unfortunately.