How to Change Mobile Menu Color (Jut A Bit)

I am creating a site with the header, the footer, and the primary menu, all with black background color. When I check how it looks, on a desktop computer, it looks fine. However, on a mobile device, the primary menu is rolled into a "hamburger menu" and is creating an issue. The rolled-up "hamburger menu" on mobile devices is showing a dark grey horizontal bars. Those bars are hard to identify on the screen because the background header is black. How can I change the color for the mobile menu, specifically the color of the rolled-up bars?