body {
    display: flex;
    flex-direction: column;
    align-items: center;
    font-family: sans-serif;
    background-color: #f4f4f4;
    margin: 0;
    padding-top: 50px;
  }
  
  h1 {
    margin-bottom: 20px;
  }
  
  .board {
    display: grid;
    grid-template-columns: repeat(3, 100px);
    grid-gap: 10px;
  }
  
  .cell {
    width: 100px;
    height: 100px;
    background-color: white;
    border: 2px solid #444;
    font-size: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
    cursor: pointer;
  }
  
  .x {
    color: red;
  }
  
  .o {
    color: blue;
  }
  
  .message {
    margin-top: 20px;
    display: none;
    flex-direction: column;
    align-items: center;
  }
  
  .message.show {
    display: flex;
  }
  
  #restartButton {
    margin-top: 10px;
    padding: 10px 20px;
    font-size: 1rem;
  }