.back-to-top {
    position: fixed;
    right: 22px;
    bottom: 22px;
    z-index: 18;
    display: grid;
    width: 48px;
    height: 48px;
    place-items: center;
    border: 2px solid #fff;
    border-radius: 50%;
    background: var(--fresh, #2f8b58);
    color: #fff;
    box-shadow: 0 8px 20px rgba(32, 51, 47, .2);
    cursor: pointer;
    opacity: 0;
    pointer-events: none;
    transform: translateY(10px);
    transition: opacity .2s ease, transform .2s ease, background .2s ease;
}

.back-to-top.is-visible { opacity: 1; pointer-events: auto; transform: translateY(0); }
.back-to-top:hover, .back-to-top:focus-visible { background: var(--navy, #182b40); }
.back-to-top span { font-size: 25px; line-height: 1; }

@media (max-width: 800px) {
    .back-to-top { right: 15px; bottom: 82px; }
}

@media (prefers-reduced-motion: reduce) {
    .back-to-top { transition: none; }
}