Fix Bug 1072988, show conditional content based on old Fx or non Fx browsers

@chrismore r?
I like the more subtle heading, I was not sure how load we wanted to be about this. From the manna doc it seemed pretty load ;) I took the structure (DIVs) from firefox/new but I agree it can be cleaner in this scenario. Thanks for the suggestions @jpetto, I am going to make those changes.