Justoverclock
I don't have any error in the debug console in Firefox. But I didn't use this since many years...
I actived and inactived your great extension 😄 and didn't see many differences.
The compiled javascript differe only with the call for yout extension.
And, in the compiled CSS, I see only a small difference.
So, I will try to play with CSS, but I think it's too simple...
Here, a screen capture about the only difference for CSS... (I added an arrow so you wont miss the difference)