#to-top {
    text-decoration: none;
    position: fixed;
    bottom: 24px;
    left: 2%;
    overflow: hidden;
    z-index: 999;
    width: 64px;
    height: 64px;
    border: none;
    text-indent: 100%;
    background: url(../images/whatsapp.png) no-repeat 0px 0px;
    background-size: 65px;
}