body {
    display: flex;
    flex-direction: column;
    align-items: center;
    justify-content: center;
    height: 100vh;
    margin: 0;
    font-family: Arial, sans-serif;
    background-color: #f9f9f9;
  }
  
  #puzzle-container {
    display: grid;
    grid-template-columns: repeat(4, 80px);
    grid-template-rows: repeat(4, 80px);
    gap: 5px;
    margin-bottom: 20px;
  }
  
  .tile {
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    font-weight: bold;
    background-color: #007bff;
    color: white;
    border-radius: 5px;
    cursor: pointer;
    user-select: none;
  }
  
  .tile.empty {
    background-color: #f0f0f0;
    cursor: default;
  }