Some problem with Firefox

Hello everyone, first of all I wanna thank you for this great plugin, very simple and useful. But I’ve a problem, as you can see in this image there’s a difference between different browsers:

in Chrome all works fine, even in Explorer O_o but in Firefox you can see that something goes wrong. Can You help me?

I’m working in local so I can’t provide u an access for this site

Kind Regard.

Cecco

https://www.ads-software.com/plugins/skt-skill-bar/