@media screen and (min-width: 900px) {
    header nav li{
    margin-left: 10px;
    }
    header nav li a{
        font-size: 12px;
    }
}
@media screen and (max-width: 767px) {
    header nav{
        display: none;
    }
    .main_banner .container{
        padding: 0 15px;
    }
}