#pagetop a {
    display: inline-block;
    position: relative;
    width: 75px;
    height: 75px;
    z-index: 999;
    right: 20px;
    bottom: 20px;
}

@media (max-width: 768px) {
    #pagetop a {
    width: 55px;
    height: 55px;
}

}