Wrong font weight – only in Firefox

Thanks for the great plugin! Works like a charm… until now ??

Comparing my website using Firefox

• with OMGF: https://www.auszeitaussee.at/?omgf=1
• without OMGF: https://www.auszeitaussee.at

you can see that the Raleway font has a way too lean font weight when OMGF is active. Chrome, Opera, etc. don’t have this problem.

Looks like the thin font get’s activated after the page load has been completed. I just can’t figure out what exactly is responsible for this bug.

I’m using the Divi theme, all plugins as well as WP is up-to-date. Any caching is disabled and cleared. Also checked the known issues.

Any ideas what could be the problem?

Many thanks in advance!

The page I need help with: [log in to see the link]