<!DOCTYPE html>
<html lang="en">
<head>
  <title>Bootstrap Example</title>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <link rel="stylesheet" href="/lib/bootstrap.min.css">
  <script src="/lib/jquery-1.12.2.min.js"></script>
  <script src="/lib/bootstrap.min.js"></script>
</head>
<body>

<div class="container">
  <h2>Collapse-down Glyph</h2>
  <p>Collapse-down icon: <span class="glyphicon glyphicon-collapse-down"></span></p>    
  <p>Collapse-down icon as a link:
    <a href="#">
      <span class="glyphicon glyphicon-collapse-down"></span>
    </a>
  </p>
  <p>Collapse-down icon on a button:
    <button type="button" class="btn btn-default btn-sm">
      <span class="glyphicon glyphicon-collapse-down"></span> Collapse
    </button>
  </p>
  <p>Collapse-down icon on a styled link button:
    <a href="#" class="btn btn-info btn-lg">
      <span class="glyphicon glyphicon-collapse-down"></span> Collapse
    </a>
  </p>
</div>

</body>
</html>