Doing a web site for this client has been an extra challenge because she is on a Mac system, I’m on Windows. I’ve been using BrowserCam to see what the pages look like and uncovered a multitude of sins through Mac IE 5.2 – which my client happens to have.
The CSS for Mac IE is stricter than Win IE so you get things like floated elements taking up full width instead of adjusting to width of contents; so if you want a horizontal menu made up from list entry items you need to specify a fixed width, which is a pain – but hey it works.
Also found a useful tip regarding background images in the stylesheet – if you specify the URL with single quotes it wont work in Mac IE, use double quotes. This tip suggested no quotes would also work, but I couldn’t get it to.