The image map itself was put in as a background on the CSS. I took the same image and loaded it into my Xara graphics program and set it to full transparency and saved it as a .png. Then you'll maintain the image map as a background, but it has the clickable area on the transparent image.
I know you expected to just code the image map as a background and have its clickable areas still work, but not going to work that way for now. Since there are more ways to skin a cat, maybe someone will come up with a working example where only one image is used and called as a BG image. Thinking on it. Sorry if my idea didn't do exactly what you wanted. I do have some other ideas.