How To Change Divi Mobile Menu Color

Apply this CSS:

/* Main header */
@media only screen and (max-width: 1000px){
#main-header{
background-color:#020202;

}
}

@media only screen and (max-width: 980px) {
#et-top-navigation span.mobile_menu_bar:before,
#et-top-navigation span.mobile_menu_bar:after {
color: white !important;
}
}