.scroll-top a {
    position: fixed;
    bottom: 20px;
    right: 20px;
    font-size: 50px;
    color: rgba(131, 131, 131, 0.50);
    outline: none;
    z-index: 999;
}
.scroll-top a:hover,
.scroll-top a:focus {
    color: rgba(131, 131, 131, 0.8);
    outline: none;
}