.rbt-btn-top a {
    border-radius: 5px;
    padding: 10px 15px 10px 15px;
    background-color: #777;
    transition: .5s;
}

.rbt-btn-top a i {
    color: #fff;
    transition: .5s;
}

.rbt-btn-top a svg {
    fill: #fff;
    transition: .5s;
    width: 50px;
}