.zap-icon {
    width: 70px;
    height: 70px;
    z-index: 999999;
    right: 20px;
    bottom: 20px;
    position: fixed;
}
.zap-icon a {
    display: block;
    width: 100%;
    height: 100%;
    background: transparent url("../img/whatsapp-icon.png");
    background-size: 100% auto;
}