I found (with Netscape) that if you have a radio button in a table that is yellow, and your background for the page is black, then the radio button background becomes black
So now you have an ugly black radio button in your yellow table. Apparently, for Netscape, the radio buttons take the page background color as their background color.
The fix.. change the page background to yellow and use a background.gif image. When the page initially loads up, you'll see everything as yellow for a split second until the background image kicks in. But now your radio buttons will look good.
With the latest IE, you don't have to do this. The radio button uses the color nearest to it for a background.