#back-to-top {
    position: fixed;
    bottom:20px;
    right:5px;
    z-index: 9999;
    width: 50px;
    height: 50px;
    text-align: center;
    line-height: 30px;
    background:none;
    color: #444;
    cursor: pointer;
    border: 0;
    border-radius: 2px;
    text-decoration: none;
    transition: opacity 0.2s ease-out;
    opacity:0;
}
#back-to-top:hover {
opacity:0;
}
#back-to-top.show {
    opacity: 1;
}

@media (min-width: 320px) and (max-width: 479px) {
#back-to-top {
bottom:85px;
right:10px;
}
}