/* Kingdom Background Music Styles - Zero Inline CSS */
.kingdom-bgm-toggle-btn {
    position: fixed;
    bottom: 22px;
    left: 22px;
    z-index: 99999;
    width: 44px;
    height: 44px;
    border-radius: 50%;
    background: rgba(18, 24, 38, 0.88);
    backdrop-filter: blur(10px);
    -webkit-backdrop-filter: blur(10px);
    border: 2px solid rgba(255, 215, 0, 0.5);
    color: #ffc107;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
    box-shadow: 0 4px 16px rgba(0, 0, 0, 0.4);
    transition: transform 0.25s ease, background-color 0.25s ease, border-color 0.25s ease, box-shadow 0.25s ease;
    outline: none;
    padding: 0;
}

.kingdom-bgm-toggle-btn:hover {
    transform: scale(1.1);
    background: rgba(30, 41, 59, 0.95);
    border-color: #ffd700;
    box-shadow: 0 6px 20px rgba(255, 215, 0, 0.3);
}

.kingdom-bgm-toggle-btn:active {
    transform: scale(0.95);
}

.kingdom-bgm-toggle-btn svg {
    width: 20px;
    height: 20px;
    transition: transform 0.2s ease;
}

.kingdom-bgm-toggle-btn.is-playing {
    color: #ffc107;
    border-color: rgba(255, 193, 7, 0.6);
    animation: kingdomBgmPulse 2.5s infinite;
}

.kingdom-bgm-toggle-btn.is-muted {
    color: #94a3b8;
    border-color: rgba(148, 163, 184, 0.35);
    background: rgba(15, 23, 42, 0.8);
    animation: none;
}

@keyframes kingdomBgmPulse {
    0% {
        box-shadow: 0 0 0 0 rgba(255, 193, 7, 0.45);
    }
    70% {
        box-shadow: 0 0 0 10px rgba(255, 193, 7, 0);
    }
    100% {
        box-shadow: 0 0 0 0 rgba(255, 193, 7, 0);
    }
}

@media (max-width: 768px) {
    .kingdom-bgm-toggle-btn {
        bottom: 16px;
        left: 16px;
        width: 40px;
        height: 40px;
    }
    .kingdom-bgm-toggle-btn svg {
        width: 18px;
        height: 18px;
    }
}