appearance of site different on IE

All of a sudden the other day our site started to look totally different on IE7 and IE8. We had not made any recent changes to the site. The biggest difference is font sizes. The site's appearance has not changed on any other browsers (I have checked FireFox, Safari and Chrome).

Does anyone have any idea how I can fix this?

The site is http://kathiskrystals.com

We are using Zen Cart v1.3.9h
Upgraded about two months ago from v1.3.8a

I could not find any other posts with this specific issue.

Thanks so much,

Kathi

I think you've specified font sizes in too many rules. You have a font-size of .8em in mainWrapper, then the same in navCatTabsWrapper, which means that font will be 80% the size of mainWrapper, and so on down the line.

Generally, you should specify a font-size in the body rule, then specific font sizes only in those rules you need to be different from everything else.

Why it changed 'all of a sudden', I don't know. It looks the same in IE8 and FF6 here - it's just IE7 (and probably IE6) where it's messed up.