@media (min-width: 769px){
    .nav_name{
        font-size: 45px!important; 
        opacity: 0.8;
    }
}
@media (max-width: 768px) and (min-width: 0px){
    .nav_name{
        font-size: 35px; 
        opacity: 0.8;
    }
}