Control Bar Gradient / Background color chance possible?

[gABBR]

Hello. Im making my own theme, and im wondering if it is currently possible to remove / chance the color of the control bar gradient, when it is locked and centered/justified as shown below. Im looking for a flat and clean look.

 

And / or if it possible to chance the color of the control bar when it is is not  centered/justified.

 

Thank you for your help

[Colin Nicholls]

Everything I know about Control Bar backgrounds is written up here.

(Firefox understands that link and goes directly to the page. It's pages 118-119.

[gABBR]

Thank you so much