How to unstyle incorrect (bold and italic) font display in Safari and Firefox? I recently noticed that some sites/blogs I visit using either Safari or Firefox are showing fonts incorrectly. My site is included which is why I realised this was a problem.  Instead of the correct styles the main font of the page is displaying bold and italic. Is this a problem on my system? How can I fix it?

Here is a picture of problem — fonts are showing in bold and italic when they should be unstyled.
When I view this page in Firefox (12.5 beta) I am seeing this text as you probably intended it - no bold and/or italic. Since you reported that the problem is occurring in both Safari and Firefox, it likely is not user preferences in both browsers, which can be set to use user-defined fonts instead of those dictated by CSS or HTML instructions. Nevertheless, I'd check each browser's display preferences first to see if this isn't the case.  

Otherwise, this may be a problem with your fonts cache, so clearing it may solve your problem. You can easily do this by opening up Terminal.app and entering the following command (this clears the font cache for the current user account; if you have other accounts, they won't be affected):

atsutil databases -removeUser