Its very strange – in the past it was always Internet Explorer and its CSS rendering that was out of sync with all the other browsers, but now – shock horror – it is Firefox that is the nightmare browser!
I have been developing a new web-application called Infacture (www.infacture.co.uk) and it renders perfectly in IE 8 and 9, Safari on the PC, Safari on the Mac, Safari on the iPad and Google Chrome… yet in Firefox 4 it does something very strange with padding, and doesnt seem to have even basic CSS3 support like in IE9 and Safari.
Firefox’s rending of div’s and in particular putting padding on the outside rather than the inside, plus its seeming lack of knowledge about putting margin-top:auto; margin-bottom:auto; to provide perfect vertical centering is a disaster when it comes to cross-browser compatability. Its now at the point that I am considering saying that the app supports all browsers EXCEPT Firefox.
Firefox – get a move on, or you are going to get left behind!