Type about:preferences#content<enter> in the address bar. Across from fonts and colors, press the Advanced button. On the bottom, turn on Allow Web Sites To Choose Their Own.

Fonts Information - Detected via Flash http://browserspy.dk/fonts-flash.php?detail=1

FredMcD said

Type about:preferences#content<enter> in the address bar. Across from fonts and colors, press the Advanced button. On the bottom, turn on Allow Web Sites To Choose Their Own. Fonts Information - Detected via Flash http://browserspy.dk/fonts-flash.php?detail=1

I already have this enabled..

You have Stylus installed.

crankygoat said

You have Stylus installed.

I uninstalled the extension and refreshed the page and the problem still persists.

You can right-click and select "Inspect Element" to open the builtin Inspector with this element selected.

• https://developer.mozilla.org/en-US/Tools/Page_Inspector/How_to/Examine_and_edit_HTML

You can check in the Rules tab in the right panel in the Inspector what font-family is used for selected text. You can check in the Font tab in the right panel in the Inspector what font is actually used because Firefox might be using a different font than specified by the website.

• https://developer.mozilla.org/en-US/Tools/Page_Inspector/How_to/Edit_fonts

Stylus may have left rules in place even if uninstalled. I'm not familiar with that extension and have not used anything similar in ages, but you might re-install it and check for removing settings (or just the font setting which is the issue).