#back-to-top {
    position: fixed;
    bottom: 20px;
    right: 20px;
    background-color: transparent !important;
    box-shadow: none !important;
}

#back-to-top:before {
    content: ' ';
    background-color: var(--color-green);
    border-radius: 50%;
    width: 48px;
    height: 48px;
    position: absolute;
    z-index: -1;
    left: 50%;
    top: 50%;
    transform: translateY(-50%) translateX(-50%);
}