IE iframe appears to inherit transparency from background

I have some css that sets a white background on my content area to be transparent so the background shows through:

.contentBg {
background:rgb(255,255,255);
background:rgba(255,255,255,0.8);
-ms-filter:alpha(opacity=80);
filter:alpha(opacity=80)
}

On one page I have an iframe of a Google map embedded. In IE9 (all other browsers appear to be fine) the iframe map is also transparent and thus appears to be inheriting the transparency from the background css.

Any idea how to over come this and give the iframe content solid background colour?

You’d have to restructure your HTML :). Transparency applies to all children. There’s no getting out of it.