.back-to-top {
    position: fixed;
    inset-inline-start: 1.5rem;
    inset-block-end: 1.5rem;
    width: 48px;
    height: 48px;
    border-radius: 50%;
    border: none;
    background: var(--color-primary);
    color: #fff;
    display: inline-flex;
    align-items: center;
    justify-content: center;
    box-shadow: var(--shadow-md);
    opacity: 0;
    pointer-events: none;
    transform: translateY(10px);
    transition: opacity 0.3s ease, transform 0.3s ease;
    z-index: 25;
}

    .back-to-top:focus-visible {
        outline: 3px solid rgba(255, 255, 255, 0.6);
    }

    .back-to-top.is-visible {
        opacity: 1;
        pointer-events: auto;
        transform: translateY(0);
    }