if we used a png transparent as a background to give it a "shape" it works on Chome, FF2, 3, SAafari 3,4 ...
but with IE (6,7,8) there is a white background that is nowhere in css or in js
at first i tought, since it an iframe, it'll need a "allowtransparency='true'" somewhere, but i can't find it...
do you want to see an exemple of this to see the problem ?