Iframe-div conflict

In a drastic attempt to reduce iframe flickering, I've made the iframe background transparent thinking that I was going conjure a div fill to use as a static background. This would work if the filler was a solid color, but I'm using opacity features for design purposes, and therefore all of the content in the iframe is set to the opacity levels predetermined in the stylesheet. (This problem is illustrated best you click on one of the menu options (in Mozilla).) Is there any way to solve this using CSS?

Site with transparent iframe; site without transparent iframe (iframe flickering, no menu).