How To Remove Padding in Title Bar When Firefox is Maximized?

[pc-v2]

I am using vertical tab mode (with sidetabs) with this options

userChrome.hidden.tabbar -> true
userChrome.autohide.sidebar -> true
userChrome.sidebar.overlap -> true
userChrome.hidden.sidebar_header -> true

And this is what I mean

The window controls also not aligned with other toolbar icons. and there's another orange color above the toolbar that I want to remove it

[black7375]

I think it's a bug, and I'll look into it further over the weekend.