/* ── Sound mute toggle button ── */
.sounds-toggle-btn {
    position: fixed;
    bottom: 80px;
    left: 20px;
    z-index: 70;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    border: 1px solid var(--border);
    background: linear-gradient(135deg, var(--surface), #1a0f2e);
    color: var(--text);
    font-size: 1.2rem;
    cursor: pointer;
    display: flex;
    align-items: center;
    justify-content: center;
    transition: transform 0.2s, opacity 0.2s, box-shadow 0.2s;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.3);
    opacity: 0.75;
}

.sounds-toggle-btn:hover {
    opacity: 1;
    transform: translateY(-2px);
    box-shadow: 0 6px 20px rgba(0, 0, 0, 0.5);
}

.sounds-toggle-btn.muted {
    opacity: 0.4;
}

/* ── Mobile ── */
@media (max-width: 600px) {
    .sounds-toggle-btn {
        bottom: 70px;
        left: 16px;
        width: 40px;
        height: 40px;
        font-size: 1.1rem;
    }
}