Smartphone Background Menu

Hi together

I made a mistake since then is the background color on the smartphone black. Unfortunately I don't know what I made.
Please have a look on the image. I'd like the background color in a different color, not in black.

What I already did is, in Wordpress under < Design - Customizer - Colors - Primary Navigation - Background > I changed the color under Smartphone to white. Unfortunately this didn't help.
Here the image therefore:

Many thank's in advance for your help.

Best regards, Hermann