/* Кнопка «Наверх» — glassmorphism */
.back-to-top {
    position: fixed;
    bottom: 24px;
    right: 24px;
    z-index: 999;
    width: 52px;
    height: 52px;
    border-radius: 50%;
    background: rgba(0, 0, 0, 0.45);
    backdrop-filter: blur(8px);
    -webkit-backdrop-filter: blur(8px);
    color: white;
    border: 1px solid rgba(255, 255, 255, 0.15);
    cursor: pointer;
    display: none;
    align-items: center;
    justify-content: center;
    font-size: 20px;
    transition: all 0.3s ease;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.2);
}

.back-to-top:hover {
    background: rgba(0, 0, 0, 0.6);
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.3);
}

.back-to-top.visible {
    display: flex;
}

@media (max-width: 768px) {
    .back-to-top {
        bottom: 16px;
        right: 16px;
        width: 46px;
        height: 46px;
        font-size: 18px;
    }
}