.lb-back-to-top {
    position: fixed;
    bottom: 2em;
    right: 0px;
    text-decoration: none;
    color: #FFF;
    background-color: #000;
    font-size: 12px;
    padding: 1em;
    display: none;
}

.lb-back-to-top:hover {    
    background-color: #CCC;
    color:#000;
}