iframe background color

I have an iframe with the id="mainimage" the correct background color for the iframe is showing correctly on firefox but not internet explorer

what am i doing wrong?



#mainimage{
width:410px;
height:500px;
float:right;
padding:0px;
margin:0px;
background-color:#90BADE;
}

The background color of the page in the iframe is probably showing in IE.
Have you tried a transparent iframe (http://www.google.com/search?q=allowtransparency+%2Biframe)?