.btn-top {
    display:none;
    position: fixed;
    bottom:20px;
    right: 40px;
    z-index:99;
    border:none;
    outline:none;
    background-color: #80bdff;
    color:#fff;
    cursor:pointer;
    padding:30px 30px;
    border-radius:50%;
    opacity: 0.5;

}
.btn-top:hover {
background-color: #117a8b;
}