#pagetop a {
    border: 1px solid #000;
    width: 51px;
    height: 51px;
    display: block;
    z-index: 999;
    background-color: #71B22C;
    padding: 12px;
}

#pagetop a::before {
    content: '';
    width: 6px;
    height: 6px;
    display: block;
    border-top: solid 1px #000;
    border-right: solid 1px #000;
    transform: rotate(-45deg);
    position: absolute;
    top: 6px;
    bottom: 0;
    left: 0;
    right: 0;
    margin: auto;
}

#pagetop a:hover {
    text-decoration: none;
}


@media screen and (max-width:768px) {

    #pagetop a {
        width: 39px;
        height: 39px;
    }

}