Hello all, Im afraid that as a last resort I am needing some help please!

I have a school website page

It looks fine in all browsers apart from IE7 where it all becomes out of alignment and I just don't know why.

If anyone could take a look at the page and the main stylesheet
I would be super grateful for any help on what I have done wrong. The forum is blocking me from posting links so message me if you have a spare few mins.

Thank you!