FF on Android seems to work fine here. What problem are you seeing?
Works fine for me with Firefox on Debian. Are you sure you don't have an extension breaking it?
I use firefox with javascript mostly off (UMatrix) but when I turned it on for fonts.googleapis.com the site and sliders all seem to worke. then I turned it on for gstatic.com fonts.gstatic.com , and not sure if that changed anything else. I'm on linux desktop