Relax. You're going to put things back to stock... make backup stylesheets if in doubt.
In your stylesheet_new;
Change the value in red, to 0 (zero)
font-family: verdana, arial, helvetica, sans-serif;
Remove the line in red.
Other than that, I'm afraid I can't help you. IE doesn't provide adequate tools to virtually adjust things. Since I'm so nice though, I used WinMerge and compared your current stylesheets to stock stylesheets from the old Zen Cart demo. More importantly, think over those previous margin values and the corrected ones.
If you think your current store is safe as it is, you should consider looking at the release notes for v1.3.5 and seek advice from others with older versions that got hacked... I'm just trying to be helpful and informative.