Image Map in WordPress Header

I have the following site:

http://breezyhillcamp.com/

I put the FaceBook logo there to link to the FaceBook page for this business, but I had to do it as part of the image for the entire header.

In order to get the link to work I tried doing an image map and that didn't work. So I created a div and the div is serving as the hyperlink and it's positioned absolutely. However, it shows up in a different spot for each browser. How do I fix it so the position is the same for every browser? Thanks!