.back-to-top {
    position: fixed;
    bottom: 20px;
    right: -90px;
    background: #007bff;
    color: white;
    width: 40px;
    height: 40px;
    text-align: center;
    line-height: 40px;
    display: block;
    border-radius: 50%;
    cursor: pointer;
    z-index: 1000;
    background-color: var(--color-primary-darken-01);
    transition: all ease .3s;
}

.back-to-top.show {
    right: 20px;
}