@media (min-width: 768px) and (max-width: 992px) {
    #main {
        top: 50px;
    }
}
@media (min-width: 550px) and (max-width: 768px) {
    #main {
        top: 50px;
    }
}
@media (max-width: 549px) {
    #main {
        top: 0;
    }
}