There are few mysteries that have plagued mankind so much as the massive problems with Internet Explorer for Windows.
Here, you can see that Internet Explorer for Windows versions five and six both do a terrible job of rendering this site. Aside from their lack of support for PNG images, they also seem to have trouble understanding the fact that
position: fixed means that the masthead should be fixed in relation to the viewing port. That is, it should hover at the top of your screen like a dainty orange butterfly. But no.
Internet Explorer for Mac version 5.2 has no such problems, it displays this site admirably. Likewise, Jessica Rabbit displays admirably; though that has nothing much to do with browsers.