Actually, Firefox and Opera render CSS quite differently. Opera has some terrible CSS bugs so it's best to check in Opera too.

Also keep in mind that IE/Win and IE/Mac render CSS very differently. So, what looks good on one IE will look very differently on the other....even IE5 and IE6 render CSS differently :/ This is the reason I don't work with CSS anymore, too much work to satisfy IE...


When I had Windows I tested in IE5.0/Win, IE6.0/Win, IE/Mac, Firefox, Opera, Konquerer, Safari...hmm that's about it, I think.