Menu colors in mobile menu

Hi, how can I change the mobile menu colors? Now the color of the secondary menu is light grey, but I would like to make it dark grey. In the customizer there's a section: secondary menu, but that colors do not appear on the site. I also would like to change the color of the word 'Menu' on the mobile site, when it's active. Now its red. I would Like to keep it the same color. http://test.blokker-fysiotherapie.nl/