:root {
      --bg: #0a0a0f;
      --bg-secondary: #12121a;
      --fg: #e8e6e3;
      --muted: #6b6b7b;
      --accent: #f59e0b;
      --accent-glow: rgba(245, 158, 11, 0.3);
      --card: #1a1a24;
      --border: #2a2a3a;
      --error: #ef4444;
      --success: #22c55e;
      --highlight: rgba(245, 158, 11, 0.15);
    }

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

    body {
      font-family: 'Space Grotesk', sans-serif;
      background: var(--bg);
      color: var(--fg);
      min-height: 100vh;
      overflow-x: hidden;
    }

    /* Background Effects */
    .bg-pattern {
      position: fixed;
      inset: 0;
      background-image: 
        radial-gradient(circle at 20% 20%, rgba(245, 158, 11, 0.08) 0%, transparent 50%),
        radial-gradient(circle at 80% 80%, rgba(245, 158, 11, 0.05) 0%, transparent 50%);
      pointer-events: none;
      z-index: 0;
    }

    .grid-lines {
      position: fixed;
      inset: 0;
      background-image: 
        linear-gradient(rgba(245, 158, 11, 0.03) 1px, transparent 1px),
        linear-gradient(90deg, rgba(245, 158, 11, 0.03) 1px, transparent 1px);
      background-size: 50px 50px;
      pointer-events: none;
      z-index: 0;
    }

    /* Typography */
    .title {
      font-size: clamp(2rem, 5vw, 3.5rem);
      font-weight: 700;
      letter-spacing: -0.02em;
      background: linear-gradient(135deg, var(--fg) 0%, var(--accent) 100%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
    }

    /* Main Container */
    .game-wrapper {
      /* max-width: 1200px; */
      margin: 0 auto;
      /* padding: 2rem; */
    }

    .game-container {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 2rem;
    }

    @media (min-width: 1024px) {
      .game-container {
        flex-direction: row;
        align-items: flex-start;
        justify-content: center;
        gap: 3rem;
      }
    }

    /* Sudoku Grid */
    .sudoku-container {
      position: relative;
      z-index: 10;
    }

    .sudoku-grid {
      display: grid;
      grid-template-columns: repeat(9, 1fr);
      gap: 1px;
      background: var(--border);
      border: 4px solid var(--accent);
      border-radius: 16px;
      overflow: hidden;
      box-shadow: 
        0 0 80px var(--accent-glow),
        0 30px 60px -15px rgba(0, 0, 0, 0.6);
      width: min(580px, 95vw);
      aspect-ratio: 1;
    }

    .sudoku-cell {
      font-family: 'JetBrains Mono', monospace;
      font-size: clamp(1.5rem, 4vw, 2.2rem);
      font-weight: 600;
      background: var(--card);
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      transition: all 0.2s ease;
      position: relative;
      user-select: none;
      min-height: 60px;
    }

    .sudoku-cell:hover {
      background: var(--highlight);
    }

    .sudoku-cell.selected {
      background: var(--accent-glow);
      box-shadow: inset 0 0 30px var(--accent-glow);
    }

    .sudoku-cell.highlighted {
      background: rgba(245, 158, 11, 0.08);
    }

    .sudoku-cell.same-number {
      background: rgba(245, 158, 11, 0.2);
    }

    .sudoku-cell.prefilled {
      color: var(--fg);
    }

    .sudoku-cell.user-input {
      color: var(--accent);
    }

    .sudoku-cell.error {
      color: var(--error);
      animation: shake 0.3s ease;
    }

    .sudoku-cell.correct {
      color: var(--success);
    }

    /* 3x3 Box borders */
    .sudoku-cell:nth-child(3n) {
      border-right: 3px solid var(--accent);
    }

    .sudoku-cell:nth-child(9n) {
      border-right: none;
    }

    .sudoku-cell:nth-child(n+19):nth-child(-n+27),
    .sudoku-cell:nth-child(n+46):nth-child(-n+54) {
      border-bottom: 3px solid var(--accent);
    }

    /* Controls Panel */
    .controls-panel {
      display: flex;
      flex-direction: column;
      gap: 1.5rem;
      width: 100%;
      max-width: 400px;
    }

    /* Number Pad */
    .number-pad {
      display: grid;
      grid-template-columns: repeat(5, 1fr);
      gap: 10px;
      width: 100%;
    }

    .num-btn {
      font-family: 'JetBrains Mono', monospace;
      font-size: 1.6rem;
      font-weight: 600;
      padding: 18px 12px;
      background: var(--card);
      border: 2px solid var(--border);
      border-radius: 12px;
      color: var(--fg);
      cursor: pointer;
      transition: all 0.2s ease;
    }

    .num-btn:hover {
      border-color: var(--accent);
      background: var(--highlight);
      transform: translateY(-3px);
      box-shadow: 0 8px 20px rgba(0, 0, 0, 0.3);
    }

    .num-btn:active {
      transform: translateY(0);
    }

    .num-btn.action-btn {
      font-size: 1rem;
      font-weight: 500;
      background: linear-gradient(135deg, var(--card) 0%, var(--bg-secondary) 100%);
    }

    .num-btn.primary {
      background: linear-gradient(135deg, var(--accent) 0%, #d97706 100%);
      color: var(--bg);
      border-color: var(--accent);
    }

    .num-btn.primary:hover {
      box-shadow: 0 0 30px var(--accent-glow);
    }

    /* Action Buttons */
    .action-buttons {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 12px;
    }

    .control-btn {
      font-family: 'Space Grotesk', sans-serif;
      font-size: 1rem;
      font-weight: 500;
      padding: 16px 20px;
      background: var(--card);
      border: 2px solid var(--border);
      border-radius: 12px;
      color: var(--fg);
      cursor: pointer;
      transition: all 0.2s ease;
    }

    .control-btn:hover {
      border-color: var(--accent);
      background: var(--highlight);
      transform: translateY(-2px);
    }

    .control-btn.active {
      background: var(--accent);
      color: var(--bg);
      border-color: var(--accent);
    }

    .control-btn.primary {
      grid-column: span 2;
      background: linear-gradient(135deg, var(--accent) 0%, #d97706 100%);
      color: var(--bg);
      border-color: var(--accent);
      font-weight: 600;
    }

    .control-btn.primary:hover {
      box-shadow: 0 0 25px var(--accent-glow);
    }

    /* Difficulty Buttons */
    .difficulty-selector {
      display: flex;
      justify-content: center;
      gap: 12px;
      flex-wrap: wrap;
    }

    .difficulty-btn {
      font-family: 'Space Grotesk', sans-serif;
      font-size: 0.95rem;
      font-weight: 500;
      padding: 12px 28px;
      background: transparent;
      border: 2px solid var(--border);
      border-radius: 10px;
      color: var(--muted);
      cursor: pointer;
      transition: all 0.2s ease;
    }

    .difficulty-btn:hover {
      border-color: var(--accent);
      color: var(--fg);
    }

    .difficulty-btn.active {
      background: var(--accent);
      color: var(--bg);
      border-color: var(--accent);
    }

    /* Stats Bar - REDUCED SIZE */
    .stats-bar {
      display: flex;
      justify-content: center;
      align-items: center;
      gap: 0.75rem;
      flex-wrap: wrap;
    }

    .timer {
      font-family: 'JetBrains Mono', monospace;
      font-size: 1.1rem;
      font-weight: 600;
      color: var(--accent);
      background: var(--card);
      padding: 8px 16px;
      border-radius: 8px;
      border: 1px solid var(--border);
    }

    .stat-box {
      background: var(--card);
      border: 1px solid var(--border);
      border-radius: 8px;
      padding: 6px 14px;
      text-align: center;
      min-width: 60px;
    }

    .stat-value {
      font-family: 'JetBrains Mono', monospace;
      font-size: 1.1rem;
      font-weight: 600;
      color: var(--accent);
      line-height: 1.2;
    }

    .stat-label {
      font-size: 0.65rem;
      color: var(--muted);
      text-transform: uppercase;
      letter-spacing: 0.05em;
    }

    /* Animations */
    @keyframes shake {
      0%, 100% { transform: translateX(0); }
      25% { transform: translateX(-5px); }
      75% { transform: translateX(5px); }
    }

    @keyframes fadeIn {
      from { opacity: 0; transform: translateY(20px); }
      to { opacity: 1; transform: translateY(0); }
    }

    .animate-in {
      animation: fadeIn 0.6s ease forwards;
    }

    .delay-1 { animation-delay: 0.1s; opacity: 0; }
    .delay-2 { animation-delay: 0.2s; opacity: 0; }
    .delay-3 { animation-delay: 0.3s; opacity: 0; }

    /* Win Modal */
    .modal-overlay {
      position: fixed;
      inset: 0;
      background: rgba(0, 0, 0, 0.85);
      backdrop-filter: blur(10px);
      display: flex;
      align-items: center;
      justify-content: center;
      z-index: 100;
      opacity: 0;
      pointer-events: none;
      transition: opacity 0.3s ease;
    }

    .modal-overlay.active {
      opacity: 1;
      pointer-events: auto;
    }

    .modal-content {
      background: var(--card);
      border: 3px solid var(--accent);
      border-radius: 24px;
      padding: 50px 60px;
      text-align: center;
      transform: scale(0.9);
      transition: transform 0.3s ease;
      box-shadow: 0 0 80px var(--accent-glow);
    }

    .modal-overlay.active .modal-content {
      transform: scale(1);
    }

    .modal-title {
      font-size: 2.5rem;
      font-weight: 700;
      margin-bottom: 1rem;
      background: linear-gradient(135deg, var(--accent) 0%, #fbbf24 100%);
      -webkit-background-clip: text;
      -webkit-text-fill-color: transparent;
      background-clip: text;
    }

    /* Notes Mode Indicator */
    .notes-indicator {
      position: absolute;
      bottom: 2px;
      right: 2px;
      font-size: 0.5rem;
      color: var(--muted);
      line-height: 1;
    }

    /* Responsive Adjustments */
    @media (max-width: 768px) {
      .game-wrapper {
        /* padding: 1rem; */
      }
      
      .sudoku-grid {
        /* width: min(95vw, 400px); */
      }
      
      .sudoku-cell {
        min-height: 45px;
        font-size: clamp(1.2rem, 3.5vw, 1.6rem);
      }
      
      .controls-panel {
        max-width: 100%;
      }
      
      .num-btn {
        padding: 14px 8px;
        font-size: 1.3rem;
      }
      
      .control-btn {
        padding: 12px 16px;
        font-size: 0.9rem;
      }
      
      .stats-bar {
        gap: 0.5rem;
      }

      .timer {
        font-size: 1rem;
        padding: 6px 12px;
      }

      .stat-box {
        padding: 5px 10px;
        min-width: 50px;
      }

      .stat-value {
        font-size: 1rem;
      }

      .stat-label {
        font-size: 0.6rem;
      }
    }

    @media (prefers-reduced-motion: reduce) {
      *, *::before, *::after {
        animation-duration: 0.01ms !important;
        transition-duration: 0.01ms !important;
      }
    }