:root {
        --bg: #0e0e0f;
        --surface: #1a1a1c;
        --surface2: #242428;
        --amber: #e8a940;
        --amber-dim: #9e6f1e;
        --amber-glow: rgba(232, 169, 64, 0.15);
        --text: #e8e0d4;
        --text-muted: #6e6860;
        --green: #4ecb71;
        --red: #e85c5c;
        --string-color: #c8a96e;
      }

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

      body {
        background: var(--bg);
        color: var(--text);
        font-family: "DM Mono", monospace;
        min-height: 100vh;
        display: flex;
        flex-direction: column;
        align-items: center;
        padding: 10px 16px 20px;
        position: relative;
        overflow-x: hidden;
      }

      body::before {
        content: "";
        position: fixed;
        inset: 0;
        background: radial-gradient(
          ellipse 60% 40% at 50% 0%,
          rgba(232, 169, 64, 0.07) 0%,
          transparent 70%
        );
        pointer-events: none;
      }

      /* Grain overlay */
      body::after {
        content: "";
        position: fixed;
        inset: 0;
        background-image: url("data:image/svg+xml,%3Csvg viewBox='0 0 200 200' xmlns='http://www.w3.org/2000/svg'%3E%3Cfilter id='n'%3E%3CfeTurbulence type='fractalNoise' baseFrequency='0.9' numOctaves='4' stitchTiles='stitch'/%3E%3C/filter%3E%3Crect width='100%25' height='100%25' filter='url(%23n)' opacity='0.04'/%3E%3C/svg%3E");
        opacity: 0.4;
        pointer-events: none;
      }

      header {
        text-align: center;
        margin-bottom: 10px;
        position: relative;
      }

      h1 {
        font-family: "Playfair Display", serif;
        font-size: 1.3rem;
        color: var(--amber);
        letter-spacing: 0.02em;
        line-height: 1;
      }

      .subtitle {
        font-size: 0.6rem;
        letter-spacing: 0.2em;
        color: var(--text-muted);
        text-transform: uppercase;
        margin-left: 8px;
        vertical-align: middle;
      }

      .main-card {
        width: 100%;
        max-width: 560px;
        background: var(--surface);
        border: 1px solid rgba(255, 255, 255, 0.06);
        border-radius: 4px;
        padding: 20px 24px;
        position: relative;
        box-shadow:
          0 32px 80px rgba(0, 0, 0, 0.6),
          0 0 0 1px rgba(232, 169, 64, 0.05);
      }

      .main-card::before {
        content: "";
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        height: 2px;
        background: linear-gradient(
          90deg,
          transparent,
          var(--amber),
          transparent
        );
      }

      /* Card top row: chord label left, diagram right */
      .card-top-row {
        display: flex;
        align-items: center;
        gap: 20px;
        margin-bottom: 14px;
      }

      /* Chord display */
      .chord-label {
        flex: 1;
        text-align: left;
        margin-bottom: 0;
        min-width: 80px;
      }

      .chord-name {
        font-family: "Playfair Display", serif;
        font-size: clamp(3rem, 10vw, 5rem);
        color: var(--amber);
        line-height: 1;
        text-shadow: 0 0 60px rgba(232, 169, 64, 0.4);
        transition: all 0.3s;
      }

      .chord-name.flash {
        animation: flash 0.3s ease;
      }

      @keyframes flash {
        0% {
          transform: scale(1);
        }
        50% {
          transform: scale(1.08);
          color: #fff;
          text-shadow: 0 0 80px rgba(232, 169, 64, 0.9);
        }
        100% {
          transform: scale(1);
        }
      }

      .chord-type {
        font-size: 0.75rem;
        letter-spacing: 0.2em;
        color: var(--text-muted);
        text-transform: uppercase;
        margin-top: 4px;
      }

      /* Fretboard diagram */
      .diagram-wrap {
        display: flex;
        justify-content: center;
        flex-shrink: 0;
        margin-bottom: 0;
      }

      .fretboard {
        position: relative;
      }

      svg.chord-svg {
        display: block;
        max-width: 100%;
        height: auto;
      }

      /* Timer + mastery side by side */
      .timer-mastery-row {
        display: flex;
        align-items: center;
        gap: 16px;
        margin-bottom: 14px;
      }

      /* Mastery bar */
      .mastery-section {
        flex: 1;
        margin-bottom: 0;
      }

      .mastery-label {
        display: flex;
        justify-content: space-between;
        font-size: 0.65rem;
        letter-spacing: 0.15em;
        color: var(--text-muted);
        text-transform: uppercase;
        margin-bottom: 8px;
      }

      .mastery-bar-bg {
        height: 4px;
        background: var(--surface2);
        border-radius: 2px;
        overflow: hidden;
      }

      .mastery-bar-fill {
        height: 100%;
        background: linear-gradient(90deg, var(--amber-dim), var(--amber));
        border-radius: 2px;
        transition: width 0.6s cubic-bezier(0.4, 0, 0.2, 1);
      }

      /* Listening indicator */
      .listen-area {
        display: flex;
        align-items: center;
        justify-content: center;
        gap: 14px;
        padding: 12px 16px;
        background: var(--surface2);
        border-radius: 3px;
        margin-bottom: 12px;
        border: 1px solid rgba(255, 255, 255, 0.04);
        min-height: 58px;
        transition: border-color 0.3s;
      }

      .listen-area.active {
        border-color: rgba(232, 169, 64, 0.3);
      }

      .pulse-ring {
        width: 36px;
        height: 36px;
        border-radius: 50%;
        background: var(--amber-glow);
        border: 2px solid var(--amber-dim);
        display: flex;
        align-items: center;
        justify-content: center;
        flex-shrink: 0;
        transition: all 0.2s;
      }

      .pulse-ring.listening {
        animation: pulse 1.2s infinite;
        border-color: var(--amber);
        background: rgba(232, 169, 64, 0.2);
      }

      .pulse-ring.detected {
        background: rgba(78, 203, 113, 0.2);
        border-color: var(--green);
        animation: none;
      }

      @keyframes pulse {
        0%,
        100% {
          box-shadow: 0 0 0 0 rgba(232, 169, 64, 0.4);
        }
        50% {
          box-shadow: 0 0 0 8px rgba(232, 169, 64, 0);
        }
      }

      .mic-icon {
        font-size: 16px;
      }

      .listen-text {
        font-size: 0.72rem;
        letter-spacing: 0.1em;
        color: var(--text-muted);
      }

      .listen-text span {
        display: block;
        color: var(--text);
        font-size: 0.8rem;
        margin-bottom: 2px;
      }

      .volume-bars {
        display: flex;
        align-items: flex-end;
        gap: 2px;
        height: 24px;
      }

      .volume-bar {
        width: 3px;
        background: var(--amber-dim);
        border-radius: 1px;
        transition: height 0.05s;
        min-height: 2px;
      }

      /* Result highlight & countdown */
      .result-highlight {
        text-align: center;
        padding: 6px 0 4px;
        display: none;
      }

      .result-score-big {
        font-family: "Playfair Display", serif;
        font-size: 3.2rem;
        line-height: 1;
        filter: drop-shadow(0 0 20px currentColor);
      }

      .result-score-pct-small {
        font-size: 1.3rem;
        opacity: 0.65;
        margin-left: 2px;
      }

      .countdown-wrap {
        display: none;
        margin-bottom: 10px;
      }

      .countdown-bar-bg {
        height: 3px;
        background: var(--surface2);
        border-radius: 2px;
        overflow: hidden;
        margin-bottom: 7px;
      }

      .countdown-bar-fill {
        height: 100%;
        background: var(--amber);
        border-radius: 2px;
        width: 100%;
      }

      .countdown-label {
        font-size: 0.58rem;
        letter-spacing: 0.14em;
        color: var(--text-muted);
        text-transform: uppercase;
        text-align: center;
      }

      /* Result section */
      .rating-section {
        display: none;
        flex-direction: column;
        gap: 10px;
      }

      .rating-section.visible {
        display: flex;
      }

      .rating-prompt {
        font-size: 0.7rem;
        letter-spacing: 0.15em;
        color: var(--text-muted);
        text-transform: uppercase;
        text-align: center;
        margin-bottom: 4px;
      }

      /* Controls */
      .controls {
        display: flex;
        gap: 10px;
        margin-top: 14px;
      }

      .btn {
        flex: 1;
        padding: 14px;
        border: 1px solid rgba(255, 255, 255, 0.1);
        background: transparent;
        color: var(--text);
        font-family: "DM Mono", monospace;
        font-size: 0.72rem;
        letter-spacing: 0.15em;
        text-transform: uppercase;
        cursor: pointer;
        border-radius: 3px;
        transition: all 0.2s;
      }

      .btn:hover {
        border-color: var(--amber-dim);
        color: var(--amber);
      }

      .btn-primary {
        background: var(--amber);
        color: #0e0e0f;
        border-color: var(--amber);
        font-weight: 500;
      }

      .btn-primary:hover {
        background: #f0b94a;
        border-color: #f0b94a;
        color: #0e0e0f;
      }

      /* Stats panel */
      .stats-panel {
        width: 100%;
        max-width: 560px;
        margin-top: 10px;
        background: var(--surface);
        border: 1px solid rgba(255, 255, 255, 0.06);
        border-radius: 4px;
        padding: 14px 16px;
      }

      .stats-title {
        font-size: 0.65rem;
        letter-spacing: 0.2em;
        color: var(--text-muted);
        text-transform: uppercase;
        margin-bottom: 16px;
      }

      .chord-stats-grid {
        display: grid;
        grid-template-columns: repeat(auto-fill, minmax(110px, 1fr));
        gap: 8px;
      }

      .chord-stat {
        background: var(--surface2);
        border-radius: 3px;
        padding: 10px 12px;
        border: 1px solid rgba(255, 255, 255, 0.04);
      }

      .chord-stat-name {
        font-family: "Playfair Display", serif;
        font-size: 1.1rem;
        color: var(--amber);
        margin-bottom: 4px;
      }

      .chord-stat-bar-bg {
        height: 3px;
        background: rgba(255, 255, 255, 0.08);
        border-radius: 2px;
        overflow: hidden;
      }

      .chord-stat-bar {
        height: 100%;
        border-radius: 2px;
        transition: width 0.5s ease;
      }

      .chord-stat-pct {
        font-size: 0.6rem;
        color: var(--text-muted);
        margin-top: 4px;
      }

      /* Setup screen */
      #setup-screen {
        width: 100%;
        max-width: 560px;
        text-align: center;
      }

      .setup-card {
        background: var(--surface);
        border: 1px solid rgba(255, 255, 255, 0.06);
        border-radius: 4px;
        padding: 28px 24px;
        position: relative;
      }

      .setup-card::before {
        content: "";
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        height: 2px;
        background: linear-gradient(
          90deg,
          transparent,
          var(--amber),
          transparent
        );
      }

      .setup-icon {
        font-size: 2.2rem;
        margin-bottom: 12px;
      }

      .setup-title {
        font-family: "Playfair Display", serif;
        font-size: 1.8rem;
        color: var(--amber);
        margin-bottom: 12px;
      }

      .setup-desc {
        font-size: 0.75rem;
        color: var(--text-muted);
        line-height: 1.7;
        margin-bottom: 20px;
        letter-spacing: 0.05em;
      }

      .chord-select-grid {
        display: grid;
        grid-template-columns: repeat(4, 1fr);
        gap: 8px;
        margin-bottom: 28px;
      }

      .chord-toggle {
        padding: 10px 6px;
        border: 1px solid rgba(255, 255, 255, 0.1);
        background: var(--surface2);
        color: var(--text-muted);
        font-family: "DM Mono", monospace;
        font-size: 0.8rem;
        cursor: pointer;
        border-radius: 3px;
        transition: all 0.15s;
        font-family: "Playfair Display", serif;
        font-size: 1rem;
      }

      .chord-toggle.selected {
        border-color: var(--amber);
        color: var(--amber);
        background: var(--amber-glow);
      }

      /* Setting row (e.g. delay slider) */
      .setting-row {
        display: flex;
        align-items: center;
        justify-content: space-between;
        gap: 12px;
        margin-bottom: 16px;
      }

      .setting-label {
        font-size: 0.65rem;
        letter-spacing: 0.15em;
        color: var(--text-muted);
        text-transform: uppercase;
        white-space: nowrap;
      }

      .setting-control {
        display: flex;
        align-items: center;
        gap: 10px;
        flex: 1;
      }

      .setting-slider {
        flex: 1;
        accent-color: var(--amber);
        cursor: pointer;
        height: 3px;
      }

      .setting-value {
        font-size: 0.72rem;
        color: var(--amber);
        min-width: 32px;
        text-align: right;
      }

      .btn-end {
        border-color: rgba(232, 92, 92, 0.3);
        color: var(--red);
      }

      .btn-end:hover {
        border-color: var(--red);
        color: var(--red);
        background: rgba(232, 92, 92, 0.08);
      }

      .mic-status {
        font-size: 0.65rem;
        letter-spacing: 0.15em;
        color: var(--text-muted);
        margin-top: 12px;
        text-transform: uppercase;
      }

      .mic-status.ok {
        color: var(--green);
      }
      .mic-status.err {
        color: var(--red);
      }

      /* Reaction Timer */
      .timer-ring-wrap {
        display: flex;
        justify-content: center;
        align-items: center;
        flex-shrink: 0;
        margin-bottom: 0;
        position: relative;
      }

      .timer-svg {
        transform: rotate(-90deg);
        filter: drop-shadow(0 0 6px rgba(232, 169, 64, 0.3));
      }

      .timer-track {
        fill: none;
        stroke: var(--surface2);
        stroke-width: 4;
      }

      .timer-arc {
        fill: none;
        stroke: var(--amber);
        stroke-width: 4;
        stroke-linecap: round;
        transition:
          stroke-dashoffset 0.1s linear,
          stroke 0.3s;
      }

      .timer-arc.slow {
        stroke: #e85c5c;
      }
      .timer-arc.medium {
        stroke: #e8a940;
      }
      .timer-arc.fast {
        stroke: #4ecb71;
      }

      .timer-center-text {
        position: absolute;
        display: flex;
        flex-direction: column;
        align-items: center;
        pointer-events: none;
      }

      .timer-seconds {
        font-family: "Playfair Display", serif;
        font-size: 1.6rem;
        color: var(--amber);
        line-height: 1;
        transition: color 0.3s;
      }

      .timer-seconds.slow {
        color: #e85c5c;
      }
      .timer-seconds.medium {
        color: #e8a940;
      }
      .timer-seconds.fast {
        color: #4ecb71;
      }

      .timer-label {
        font-size: 0.55rem;
        letter-spacing: 0.18em;
        color: var(--text-muted);
        text-transform: uppercase;
        margin-top: 2px;
      }

      .speed-badge {
        display: inline-block;
        font-size: 0.6rem;
        letter-spacing: 0.12em;
        text-transform: uppercase;
        padding: 2px 8px;
        border-radius: 2px;
        margin-left: 8px;
        vertical-align: middle;
      }
      .speed-badge.fast {
        background: rgba(78, 203, 113, 0.15);
        color: #4ecb71;
        border: 1px solid rgba(78, 203, 113, 0.3);
      }
      .speed-badge.medium {
        background: rgba(232, 169, 64, 0.15);
        color: #e8a940;
        border: 1px solid rgba(232, 169, 64, 0.3);
      }
      .speed-badge.slow {
        background: rgba(232, 92, 92, 0.15);
        color: #e85c5c;
        border: 1px solid rgba(232, 92, 92, 0.3);
      }

      @media (max-width: 480px) {
        .main-card {
          padding: 16px 14px;
        }
        .card-top-row {
          flex-direction: column;
          align-items: center;
          gap: 8px;
        }
        .chord-label {
          text-align: center;
        }
        .chord-select-grid {
          grid-template-columns: repeat(3, 1fr);
        }
      }