Quoting Mark Rogers mark@quarella.co.uk:
As you can see, its not surprising that the bits you're having problems with got confused!
Thank you Mark, I will go through each bit and change them to see what works. The style sheet is one I got from a CSS site somewhere, but a couple of years ago, and I can't remember when. A lot of those hacky bits might be to work round issues that browsers have now put right themselves anyway.
Thanks again for the advice.