|A Cascading Style Sheet document is usually where all the formatting of the web page is done. I'm not familiar with tor, conduit, DAP, uTorrent, or shopper's report, so you'll have to check each addon's options for items related to blocking CSS documents.|
You haven't made changes to the Firefox about:config file, have you? I doubt it, but just checking.
Are there any sites listed as exceptions in the Load Images Automatically (Content tab) option? Once again, I doubt it.
Another cause as to why a CSS document and other web items fail to load is because of a poor Internet Connection. If you have too many items connected to the Internet, possibly downloading updates or even malware, they could be utilizing too much bandwidth causing your websites to load slowly or not at all. I'd do a full scan with Malwarebytes and/or SuperAntispyware. The latter will find tracking cookies which aren't necessarily malicious, but a good thing to clean up regularly.
Apologies if I don't respond to your reply immediately. I don't check this site daily.