Mobile Nav Style

Apparently this is not a support issue so hopefully someone in the community can provide a solution… (pretty please!)

Using the Practis child theme but having to use a solid colour across the main nav as the default background ribbon doesn’t show in mobile view so only shows white text on white background.
Can someone please advise what the CSS code is to add a background colour to the mobile nav only…
Found this in the stylesheet but the color value only applies to the nav title it seems

/*** MOBILE STYLES ***/
.navbar .brand { text-shadow: 0 0px 0 #fff; color:#333; font-size:14px; }