* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}

body {
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
    background: linear-gradient(135deg, #1a1a2e 0%, #16213e 50%, #0f3460 100%);
    min-height: 100vh;
    color: #fff;
    overflow-x: hidden;
}

.container {
    max-width: 1400px;
    margin: 0 auto;
    padding: 20px;
}

header {
    text-align: center;
    margin-bottom: 30px;
}

h1 {
    font-size: 3rem;
    font-weight: 300;
    letter-spacing: 4px;
    background: linear-gradient(90deg, #e94560, #f39c12, #e94560);
    background-size: 200% auto;
    -webkit-background-clip: text;
    -webkit-text-fill-color: transparent;
    animation: shimmer 3s linear infinite;
}

@keyframes shimmer {
    to { background-position: 200% center; }
}

.subtitle {
    color: #888;
    margin-top: 10px;
    font-size: 1.1rem;
}

/* Controls */
.controls {
    display: flex;
    justify-content: center;
    align-items: center;
    gap: 40px;
    margin-bottom: 40px;
    flex-wrap: wrap;
}

.control-group {
    display: flex;
    flex-direction: column;
    align-items: center;
    gap: 8px;
}

.control-group label {
    font-size: 0.85rem;
    color: #aaa;
    text-transform: uppercase;
    letter-spacing: 1px;
}

input[type="range"] {
    width: 150px;
    height: 6px;
    -webkit-appearance: none;
    background: linear-gradient(90deg, #333, #555);
    border-radius: 3px;
    cursor: pointer;
}

input[type="range"]::-webkit-slider-thumb {
    -webkit-appearance: none;
    width: 18px;
    height: 18px;
    background: #e94560;
    border-radius: 50%;
    cursor: pointer;
    box-shadow: 0 0 10px rgba(233, 69, 96, 0.5);
    transition: transform 0.2s;
}

input[type="range"]::-webkit-slider-thumb:hover {
    transform: scale(1.2);
}

select {
    padding: 10px 20px;
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 8px;
    color: #fff;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s;
}

select:hover {
    background: rgba(255, 255, 255, 0.15);
    border-color: #e94560;
}

select option {
    background: #1a1a2e;
    color: #fff;
}

/* Tuning Control */
.tuning-control {
    display: flex;
    align-items: center;
    gap: 8px;
}

.tuning-label {
    font-size: 0.85rem;
    color: #888;
    min-width: 45px;
}

.just-toggle {
    background: none;
    border: none;
    cursor: pointer;
    padding: 4px;
}

.toggle-track {
    display: block;
    width: 36px;
    height: 20px;
    background: rgba(255, 255, 255, 0.15);
    border-radius: 10px;
    position: relative;
    transition: background 0.2s;
}

.toggle-thumb {
    position: absolute;
    top: 2px;
    left: 2px;
    width: 16px;
    height: 16px;
    background: #888;
    border-radius: 50%;
    transition: all 0.2s;
}

.just-toggle.active .toggle-track {
    background: rgba(233, 69, 96, 0.4);
}

.just-toggle.active .toggle-thumb {
    left: 18px;
    background: #e94560;
    box-shadow: 0 0 8px rgba(233, 69, 96, 0.6);
}

.key-select {
    padding: 6px 10px;
    font-size: 0.85rem;
    min-width: auto;
    width: 55px;
}

.key-select.hidden {
    display: none;
}

/* Duet Button */
.duet-btn {
    display: flex;
    align-items: center;
    gap: 10px;
    padding: 12px 24px;
    background: linear-gradient(135deg, #333, #444);
    border: 2px solid #555;
    border-radius: 30px;
    color: #aaa;
    font-size: 1rem;
    cursor: pointer;
    transition: all 0.3s;
}

.duet-btn:hover {
    border-color: #e94560;
    color: #fff;
}

.duet-btn.active {
    background: linear-gradient(135deg, #e94560, #f39c12);
    border-color: transparent;
    color: #fff;
    box-shadow: 0 0 30px rgba(233, 69, 96, 0.4);
}

.duet-icon {
    font-size: 1.5rem;
}

/* Piano Container */
.piano-container {
    display: flex;
    flex-direction: column;
    align-items: center;
    margin-bottom: 30px;
}

.octave-labels {
    display: flex;
    width: 100%;
    max-width: 1200px;
    justify-content: space-around;
    margin-bottom: 10px;
    color: #666;
    font-size: 0.9rem;
}

.piano {
    display: flex;
    position: relative;
    background: linear-gradient(180deg, #2a2a3a, #1a1a2a);
    padding: 20px 15px 15px;
    border-radius: 10px;
    box-shadow:
        0 20px 60px rgba(0, 0, 0, 0.5),
        inset 0 2px 0 rgba(255, 255, 255, 0.1);
}

/* Piano Keys */
.key {
    position: relative;
    cursor: pointer;
    transition: all 0.08s ease-out;
    user-select: none;
}

.key.white {
    width: 50px;
    height: 200px;
    background: linear-gradient(180deg, #f8f8f8 0%, #fff 10%, #e8e8e8 100%);
    border: 1px solid #ccc;
    border-radius: 0 0 6px 6px;
    margin: 0 1px;
    z-index: 1;
    box-shadow:
        0 4px 8px rgba(0, 0, 0, 0.3),
        inset 0 -2px 4px rgba(0, 0, 0, 0.1);
}

.key.white:hover {
    background: linear-gradient(180deg, #fff 0%, #fff 10%, #f0f0f0 100%);
}

.key.white.active {
    background: linear-gradient(180deg, #e0e0e0 0%, #d8d8d8 100%);
    transform: translateY(3px);
    box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
}

.key.white.ai-active {
    background: linear-gradient(180deg, #ffe0e5 0%, #ffd0d8 100%);
    box-shadow:
        0 4px 8px rgba(0, 0, 0, 0.3),
        0 0 20px rgba(233, 69, 96, 0.4);
}

.key.black {
    width: 34px;
    height: 120px;
    background: linear-gradient(180deg, #333 0%, #1a1a1a 100%);
    border-radius: 0 0 4px 4px;
    position: absolute;
    z-index: 2;
    box-shadow:
        0 4px 10px rgba(0, 0, 0, 0.5),
        inset 0 -4px 8px rgba(0, 0, 0, 0.4),
        inset 0 2px 4px rgba(255, 255, 255, 0.1);
}

.key.black:hover {
    background: linear-gradient(180deg, #444 0%, #2a2a2a 100%);
}

.key.black.active {
    background: linear-gradient(180deg, #222 0%, #111 100%);
    transform: translateY(2px);
    height: 118px;
    box-shadow:
        0 2px 5px rgba(0, 0, 0, 0.4),
        inset 0 -2px 4px rgba(0, 0, 0, 0.4);
}

.key.black.ai-active {
    background: linear-gradient(180deg, #5a2030 0%, #3a1520 100%);
    box-shadow:
        0 4px 10px rgba(0, 0, 0, 0.5),
        0 0 15px rgba(233, 69, 96, 0.5);
}

/* Key Labels */
.key-label {
    position: absolute;
    bottom: 10px;
    left: 50%;
    transform: translateX(-50%);
    font-size: 0.7rem;
    color: #999;
    pointer-events: none;
}

.key.black .key-label {
    color: #666;
    bottom: 8px;
    font-size: 0.6rem;
}

/* Keyboard Hints */
.keyboard-hint {
    text-align: center;
    padding: 20px;
    background: rgba(255, 255, 255, 0.05);
    border-radius: 10px;
    margin-top: 20px;
}

.keyboard-hint h3 {
    color: #888;
    font-weight: 400;
    margin-bottom: 15px;
    font-size: 1rem;
}

.key-mappings {
    display: flex;
    flex-direction: column;
    gap: 8px;
}

.mapping-row {
    font-size: 0.9rem;
    color: #666;
}

.white-keys {
    color: #aaa;
}

.black-keys {
    color: #777;
}

/* Duet Indicator */
.duet-indicator {
    position: fixed;
    bottom: 30px;
    right: 30px;
    background: rgba(233, 69, 96, 0.9);
    padding: 15px 25px;
    border-radius: 30px;
    box-shadow: 0 10px 40px rgba(233, 69, 96, 0.4);
    transition: all 0.3s;
}

.duet-indicator.hidden {
    opacity: 0;
    transform: translateY(20px);
    pointer-events: none;
}

.indicator-content {
    display: flex;
    align-items: center;
    gap: 10px;
    font-weight: 500;
}

.pulse {
    width: 10px;
    height: 10px;
    background: #fff;
    border-radius: 50%;
    animation: pulse 1.5s ease-in-out infinite;
}

@keyframes pulse {
    0%, 100% { opacity: 1; transform: scale(1); }
    50% { opacity: 0.5; transform: scale(1.2); }
}

/* Responsive */
@media (max-width: 1200px) {
    .key.white {
        width: 40px;
        height: 160px;
    }

    .key.black {
        width: 28px;
        height: 100px;
    }
}

@media (max-width: 768px) {
    .key.white {
        width: 30px;
        height: 130px;
    }

    .key.black {
        width: 22px;
        height: 80px;
    }

    .controls {
        gap: 20px;
    }

    h1 {
        font-size: 2rem;
    }
}