Roll-over CSS Image Map

I have created a roll-over enabled image map with css (see http://www.alistapart.com/articles/imagemap/) for more details...but I can only get it to work on my resolution, when I change the resolution the rollovers are out of place (obviously because I have a fixed position).

Is there a way to have them be correct in any resolution? I would like to have the image in the background centered...which I figure is what is messing this up. Any ideas would be appreciated. Thanks.

The link is: intuitiontech.com/msc/