I've just upgraded to FF 57 and websites that use their own fonts have stopped displaying text.
I know this is a problem others have had, e.g. Firefox doesn't display website text, but the solutions there have not worked. Safe mode does not help either, the problem only goes away if I uncheck the custom fonts option in Preferences.
I have custom fonts installed as well (from TexLive and and a couple more) so I'm thinking that might be the cause.
Any ideas on how to troubleshoot this?
Example from Github: