Customize Sidebar Colors Only?

Hi,
I’m trying to figure out a way to change just the top color of the sidebar. The area I’m talking about is the part that contains the Social Media icons. By default, it’s the color that you set as Primary in the Theme Customizer. I’d like to have it be it’s own color if possible.

Also, on a mobile display, that area would display an arrow for visitors to click which would expand the sidebar outward. The problem is, when that happens, the Social Media icons which were once on a background (in my case Red), now sit on a white background. This is a problem because I have a couple icons that are light colors so they stand out on the Red background. When the mobile sidebar is expanded, those icons are almost invisible because they’re now on a white background.

Any ideas how I can accomplish these two things? For the second part, I’d just like to keep the Social Media icons on the same background color they were (i.e. the same color as the mobile sidebar button). Thanks!