Issues: 1) replaces to Arial!!! My eyes are bleeding. Should better have a user-configured default sans font; 2) replaces monospaced to Arial!!! My eyes are bleeding. Should better have a user-configured default monospace font; 3) replaces serif to Arial!!! My eyes are bleeding. Should better have a user-configured default serif font. 4) Probably breaks font metrics, so on-line editors misplace text caret. For me it's definitely broken. Otherwise extension is working good, it really makes all those mad designers to behaviour nice. But with 1-4 problems, this extension is useless.

Thanks Rudie, it works fine with Firefox 68.0.2

Amazing extension - thank you so much. Some web fonts render terribly on my monitor and this allows me to see everything clearly again.