Individual variable sliders per font

[slobzheninov]

Hi! First of all, thanks a lot for this awesome tool!

I was looking for a way to preview multiple instances of a variable font, but it seems to be impossible because the sliders are global. That made me wondering why it is so? I think it would be useful to have individual sliders for each uploaded font in addition to the global ones. Global sliders then could be used to override the corresponding individual sliders, one at a time. This way the user could upload a variable font multiple times, set them to different weights and then globally change width/slant/opt size.

Just a suggestion!