Maybe some fonts got hosed. Arial and Helvetica are the main ones. Do they work in a Word Processor?

I didn’t find out what went wrong but I reset my font in Firefox>Tools>Options.
Something unset it.

There’s an option in Firefox to override with your own fonts in that menu

Tools->Options->Content->Advanced

Then if you uncheck “allow pages to choose their own fonts, instead of my selections above”

It will go with whatever you’ve defined instead of using what the site intended.