Hello,

Add this code to the Theme Settings > Custom CSS:

.basel-header-overlap .main-header:not(.header-split).act-scroll .main-nav .menu>li>a {
    color:black;
}
.basel-header-overlap .main-header:not(.header-split).act-scroll .main-nav .menu>li.current-menu-item>a {
    color:black;
}

Best Regards