Top & Side Category Menus To Have Different Colors

I'm using an out-of-the-box install of version 4.9. My question is regarding the design. I'd like to have a top menu and a side menu with the categories but I'd like them to have different background colors. I've seen it done where the top menu uses the Color>Menu of the Theme editor and the side menu uses the Color>Sidebar of the Theme editor but I cannot find any blocks in the default responsive theme that are effected by the Color>Sidebar option. Can someone tell me how I can get the two menus to use different settings?

It can be done with custom CSS (CSS section in the Theme editor)

Please provide or PM us with the URL of your website so that we can post required code here

Thank you for your help. The temporary site is

I have been able to make a change to the background color of the side menu using the custom CSS but I can't get a change to the font color.