/* Reset styles */
    * {
      margin: 0; padding: 0; box-sizing: border-box;
    }
    body {
      font-family: Arial, sans-serif;
      background: #f5f5f5;
      color: #333;
      line-height: 1.6;
    }
    header, footer {
      background: #fff;
      text-align: center;
      padding: 15px;
    }
    .container {
      max-width: 1000px;
      margin: 20px auto;
      background: #fff;
      padding: 20px;
      border-radius: 8px;
      box-shadow: 0 4px 6px rgba(0,0,0,0.1);
    }
    h1, h2 {
      margin-bottom: 20px;
    }
    /* Tabs Navigation */
    .tabs {
      display: flex;
      border-bottom: 2px solid #007BFF;
      margin-bottom: 20px;
    }
    .tabs button {
      flex: 1;
      padding: 10px;
      border: none;
      background: none;
      border-bottom: 4px solid transparent;
      cursor: pointer;
      font-size: 1rem;
      color: #007BFF;
      transition: all 0.3s;
    }
    .tabs button.active {
      border-bottom-color: #007BFF;
      font-weight: bold;
    }
    .tabcontent {
      display: none;
    }
    .tabcontent.active {
      display: block;
    }
    /* Game Control Panel */
    .game-controls {
      text-align: center;
      margin-bottom: 20px;
    }
    .game-controls input, .game-controls select {
      padding: 5px;
      margin: 0 10px;
      font-size: 1rem;
    }
    .game-controls button {
      padding: 7px 15px;
      background: #007BFF;
      color: #fff;
      border: none;
      border-radius: 4px;
      cursor: pointer;
      margin: 0 5px;
      transition: background 0.3s;
    }
    .game-controls button:hover {
      background: #0056b3;
    }
    .status {
      text-align: center;
      margin-bottom: 20px;
      font-size: 1.1rem;
    }
    /* Board Display */
    #boardContainer {
      margin: 0 auto;
      width: 320px; /* for 4x4, each tile 75px + gap */
      display: grid;
      gap: 5px;
      justify-content: center;
    }
    /* We'll dynamically set grid-template-columns based on board size */
    .tile {
      background: #007BFF;
      color: white;
      font-size: 2rem;
      font-weight: bold;
      border-radius: 5px;
      display: flex;
      align-items: center;
      justify-content: center;
      cursor: pointer;
      user-select: none;
      transition: background 0.3s;
    }
    .tile.empty {
      background: #ccc;
      cursor: default;
    }
    .tile.correct {
      background: green;
    }
    .tile.wrong {
      background: red;
    }
    /* Records Table */
    #recordsTable {
      width: 100%;
      border-collapse: collapse;
      margin-top: 10px;
    }
    #recordsTable th, #recordsTable td {
      border: 1px solid #007BFF;
      padding: 8px;
      text-align: center;
    }
    #recordsTable th {
      background: #007BFF;
      color: white;
    }
    #recordsArea {
      max-height: 400px;
      overflow-y: auto;
      margin-top: 10px;
    }
    .btn-clear {
      padding: 7px 15px;
      background: #e74c3c;
      color: #fff;
      border: none;
      border-radius: 4px;
      cursor: pointer;
      margin-top: 10px;
      transition: background 0.3s;
    }
    .btn-clear:hover {
      background: #c0392b;
    }
    footer {
      margin-top: 20px;
      box-shadow: 0 -2px 4px rgba(0,0,0,0.1);
    }