<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
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<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>btn ADD REMOVE CLASS</title>
</head>
<body>
<div class="main_div">
<button type="button" class="btn">Button</button>
<hr>
<div class="box">
<h2>Lorem Ipsum dolor sit amet</h2>
</div></div>
<p class="text-center top_spac"> Create by <a target="_blank" href="https://in.linkedin.com/in/sunil-rajput-nattho-singh">Sunil Rajput</a></p>
</body>
</html>
