It's not possible in HTML, and the CSS isn't that advanced. Basically

or in .css:
img.foreground
{
z-index: 3;
}
then

I think unz-indexed elements (i.e. everything else) defalt to zero, so 1 would work, too... but you never know when you're going to want to slide something in between.
Or you can simply add the foreground image last, which would put it on top of everything else.
I think a steering wheel would be another great idea for a foreground.
---
peddling the funny around since 09/24/2002