body {
    text-align: center;
    font-family: Arial, sans-serif;
    margin-top: 50px;
  }
  
  input {
    padding: 10px;
    width: 250px;
  }
  
  button {
    padding: 10px 20px;
  }
  
  .valid {
    color: green;
  }
  
  .invalid {
    color: red;
  }