Hello,

I saw the screenshot you attached. Please try adding the following Custom CSS in the Custom CSS for the Mobile area under Theme Settings >> Custom CSS.

.mobile-nav .searchform input[type=text]::placeholder {
color: white;
}

.searchform .searchsubmit, .mobile-nav-tabs li,  {
color: white;
}

.mobile-nav-tabs li {
color: white;
}

.site-mobile-menu li a {
color: white;
}

Regard’s.
Xtemos Studio.