Hide the gray line + customize groups font and color

Is it possible to make an option allowing us to remove the gray line along with the arrow that comes with it?

I for one would prefer to access settings in another way.

Also, an option to customize the look of the groups buttons would be nice. Like, changing the green color to a color of our choosing, the font and the color of the group name as well as changing the color and the font of the not selected (not active) group buttons.