Sorry, Firefox is not able to view web sites that require IE compatibility mode. Those sites use non-standard code that works only in IE.

The site worked before. If you check out the site in question , you'll see it was designed for Firefox and was browser neutral. I DEVELOPED THE SITE! Basically put, as soon as my mouse goes over the text area of the page, it changes the font to bold. This happened in IE as well, but went away when I made IE use compatibility mode.

I see the same in Google Chrome.

Looks that is is caused by a missing close </a> in <a name="skip_nav">

<span class="pathway"><span class="pathway">Home </span>
</span><br><hr>
<P>
<a name="skip_nav">

The currently used HTML5 parser doesn't like such omissions and reopens the a tags for each P container and applies the CSS rules for hover.
It works if I disable the HTML5 parser.

You rock! I've been beating myself up for months looking for this, and it was that simple. Correction made and the site works perfectly. Sorry to report an HTML error as a Firefox error. I should have known better. After all, you're NOT Microsoft!

You're welcome

I used the DOM Inspector and moved the cursor up in the left pane with the computed CSS in the right pane while hovering the mouse on the website until I saw the font-weight bold changing from 700 to 400 and then checked the code of that A element.