I'm an undergraduate student who recently ( about 3 months) got a part time employment of managing a website, to replace a close friend who worked there. I came into the job knowing only a bit about CSS and HTML, and nothing at all about Drupal. I received about 7 days of training from my friend, but the rest has been learning on my own, so I'm still very green. However, I don't know how to approach this problem that sprung up about 2 weeks ago, when I found that the site doesn't display properly on Firefox or IE. It seems that the blocks that are built from drupal aren't having CSS applied to them, but I'm not very sure. Any help at all would be wonderful, as the issue I'm having is not knowing where the issue lies. The site is http://confluencenter.arizona.edu/.
First thing is first. Enable css aggregation
under admin > configuration > performance
It is likely a hosting issue and not a Drupal issue. Talk to UITS and see if they are doing anything out of the ordinary.