/* Reset default browser styles */
* {
      margin: 0;
      padding: 0;
      box-sizing: border-box;
  }
  
  body {
      font-family: Arial, sans-serif;
      background-color: #f4f7f9;
      background-image: url('bg.jpg');
    background-size: cover; /* Ensures the image covers the entire background */
    background-position: center; /* Centers the background image */
    background-attachment: fixed; 
      color: #333;
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
      margin: 0;
  }
  
  .container {
      background-color: #fff;
      border-radius: 8px;
      box-shadow: 0 0 15px rgba(0, 0, 0, 0.1);
      padding: 20px;
      width: 400px;
      text-align: center;
  }
  
  h1 {
      font-size: 24px;
      color: #007BFF;
      margin-bottom: 20px;
  }
  
  input[type="text"] {
      width: calc(100% - 22px);
      padding: 10px;
      margin-bottom: 10px;
      border: 2px solid #007BFF;
      border-radius: 5px;
      font-size: 16px;
      outline: none;
      transition: border-color 0.3s ease;
  }
  
  input[type="text"]:focus {
      border-color: #0056b3;
  }
  
  button {
      background-color: #007BFF;
      border: none;
      color: white;
      padding: 10px 20px;
      border-radius: 5px;
      cursor: pointer;
      font-size: 16px;
      transition: background-color 0.3s ease;
  }
  
  button:hover {
      background-color: #023872;
  }
  
  p {
      font-size: 18px;
      margin-top: 20px;
      font-weight: bold;
  }
  
  @media (max-width: 480px) {
      .container {
          width: 90%;
          padding: 15px;
      }
  
      h1 {
          font-size: 20px;
      }
  
      input[type="text"] {
          font-size: 14px;
      }
  
      button {
          font-size: 14px;
      }
  
      p {
          font-size: 16px;
      }
  }
  .valid-output {
      color: rgb(4,255,0); /* Green for valid card */
      font-weight: bold;
      margin-top: 10px;
      font-size: 1.2em;
  }
  
  /* Invalid output styling */
  .invalid-output {
      color: rgb(255, 60, 0); /* Red for invalid card */
      font-weight: bold;
      margin-top: 10px;
      font-size: 1.2em;
  }