changes colors

How can I change the background of the menu located in the 'left-2' position? The background remains blue. I have already adjusted this in the layout module for 'left-2' (see attachment 1). As a test, I changed the corner settings, and those did update (see attachment 2).
Is it possible to change everything that is currently blue to a custom color of my choice (I would like to use #7A2E1E)?