#fsd-back-to-top {
    position: fixed;
    right: 18px;
    bottom: 18px;
    z-index: 1000; // 999999;

    width: 52px;
    height: 52px;
    border-radius: 999px;
    border: 0;

    cursor: pointer;
    display: grid;
    place-items: center;

    background: rgba(20, 20, 20, 0.85);
    color: #fff;

    box-shadow: 0 6px 22px rgba(0, 0, 0, 0.25);
    transition: transform 120ms ease, opacity 200ms ease, background 200ms ease;

    /* Start: unsichtbar */
    opacity: 0;
    pointer-events: none;
    transform: translateY(6px);
}

#fsd-back-to-top.is-visible {
    opacity: 0.9;
    pointer-events: auto;
    transform: translateY(0);
}

#fsd-back-to-top:hover {
    transform: translateY(-2px);
    background: rgba(20, 20, 20, 0.95);
}

#fsd-back-to-top:active {
    transform: translateY(0);
}

#fsd-back-to-top:focus {
    outline: 2px solid rgba(255, 255, 255, 0.65);
    outline-offset: 2px;
}

#fsd-back-to-top svg {
    width: 22px;
    height: 22px;
    display: block;
}

@media (max-width: 420px) {
    #fsd-back-to-top {
        right: 12px;
        bottom: 12px;
        width: 46px;
        height: 46px;
    }
}