<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <link rel="stylesheet" href="./style.css">
</head>
<body>
  <section>
    <div class="clock" data-format='12'>
      <h1>00 : 00 : 00 AM</h1>
    </div>
    <div class="format">
      <h1>Format</h1>
      <button data-format='12'>12hours</button>
      <button data-format='24'>24hours</button>
    </div>
  </section>
  <script src="./main.js">