Hello,
Add this code into custom.css file and after that clear cache.
.header-type-4 .main-nav .menu > li > a,
.fixed-header .menu > li > a,
.header-type-4 .main-nav .menu > li.current-menu-item > a {
color: #fff;
}
.header-type-4 .main-nav .menu > li > a:hover,
.fixed-header .menu > li > a:hover{
color:grey;
}
.fixed-header {
color:#000;
}
Regards,
Robert Hall.