* {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      min-height: 100vh;
      display: flex;
      justify-content: center;
      align-items: center;
      background: #1e1e1e;
      font-family: Arial, Helvetica, sans-serif;
      color: white;
    }

    .container {
      display: flex;
      flex-direction: column;
      align-items: center;
      gap: 20px;
    }

    .board {
      width: 420px;
      height: 420px;
      display: grid;
      grid-template-columns: repeat(4, 1fr);
      grid-template-rows: repeat(4, 1fr);
      gap: 8px;
      background: #111;
      padding: 8px;
      border-radius: 12px;
    }

    .tile {
      display: flex;
      justify-content: center;
      align-items: center;
      background: #4f8cff;
      border-radius: 10px;
      font-size: 2rem;
      font-weight: bold;
      cursor: pointer;
      user-select: none;
      transition: 0.15s;
    }

    .tile:hover {
      transform: scale(1.03);
    }

    .empty {
      background: #222;
      cursor: default;
    }

    button {
      padding: 10px 18px;
      border: none;
      border-radius: 8px;
      font-size: 1rem;
      cursor: pointer;
    }

    .info {
      font-size: 1.2rem;
    }