<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet"
href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</head>
<body>
<div class="container">
<div class="panel-group" id="accordion">
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a data-toggle="collapse" data-parent="#accordion"
href="#collapse1-id">Click to collapse 1</a>
</h4>
</div>
<div id="collapse1-id" class="panel-collapse collapse in">
<div class="panel-body">
1. Bootstrap is a free and open-source front-end web framework for designing <br />
websites and web applications. <br />
It contains HTML and CSS.</div>
</div>
</div>
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a data-toggle="collapse" data-parent="#accordion"
href="#collapse2-id">Click to collapse 2</a>
</h4>
</div>
<div id="collapse2-id" class="panel-collapse collapse">
<div class="panel-body">
2. Bootstrap is a free and open-source front-end web framework for designing <br />
websites and web applications. <br />
It contains HTML and CSS.</div>
</div>
</div>
<div class="panel panel-default">
<div class="panel-heading">
<h4 class="panel-title">
<a data-toggle="collapse" data-parent="#accordion"
href="#collapse3-id">Click to collapse 3</a>
</h4>
</div>
<div id="collapse3-id" class="panel-collapse collapse">
<div class="panel-body">
3. Bootstrap is a free and open-source front-end web framework for designing <br />
websites and web applications. <br />
It contains HTML and CSS.</div>
</div>
</div>
</div>
</div>
</body>
</html>
