countdown.html

<!DOCTYPE html>
<html>
<head>
  <title>Countdown Timer</title>
  <style>
    body {
      font-family: Arial, sans-serif;
      display: flex;
      justify-content: center;
      align-items: center;
      height: 100vh;
      background-color: #f0f0f0;
    }
    .container {
      text-align: center;
      background-color: #fff;
      padding: 20px;
      border-radius: 10px;
      box-shadow: 0 0 10px rgba(0, 0, 0, 0.1);
    }
  </style>
</head>
<body>
  <div class="container">
    <h2>Countdown Timer</h2>
    <p id="timer">30</p>
  </div>

 <script src="script.js"></script>
</body>
</html>