.btn-up{
    display: none;
    position: fixed;
    right: 30px;
    bottom: 30px;
    width: 90px;
    height: 90px;
    background: rgba(122,122,122,.15) url("../img/arr-up.png") no-repeat top 37px center;
    -webkit-border-radius: 50%;
    -moz-border-radius: 50%;
    border-radius: 50%;
    cursor: pointer;
}