body {
    font-family: Arial, sans-serif;
    background-color: #f4f4f4;
    text-align: center;
    margin: 0;
    padding: 0;
  }
  
  .container {
    max-width: 800px;
    margin: auto;
    padding: 20px;
  }
  
  h1 {
    font-size: 2rem;
    margin-bottom: 20px;
  }
  
  #grid {
    display: grid;
    grid-template-columns: repeat(7, 1fr);
    grid-gap: 5px;
    margin: 20px auto;
    max-width: 350px;
  }
  
  .square {
    font-size: 24px;
    width: 50px;
    height: 50px;
    display: flex;
    align-items: center;
    justify-content: center;
    border: 2px solid #ccc;
    background-color: white;
    cursor: pointer;
  }
  
  .square.clicked {
    background-color: green;
    color: white;
  }
  
  .square.highlighted {
    background-color: red;
    color: white;
  }
  
  button {
    padding: 10px 20px;
    font-size: 16px;
    margin-top: 20px;
    cursor: pointer;
  }
  
  button:hover {
    background-color: #ddd;
  }
  
  #endMessage {
    color: red;
    font-size: 1.5rem;
    margin-top: 20px;
  }