<!DOCTYPE html>
<html>
<head>
<meta name="viewport" content="width=device-width, initial-scale=1, maximum-scale=1, user-scalable=no">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/3.4.1/css/bootstrap.min.css" integrity="sha384-HSMxcRTRxnN+Bdg0JdbxYKrThecOKuH5zCYotlSAcp1+c8xmyTe9GYg1l9a69psu" crossorigin="anonymous">
<style>
.sr-only {
position: absolute;
width: 1px;
height: 1px;
padding: 0;
margin: -1px;
overflow: hidden;
clip: rect(0, 0, 0, 0);
border: 0;
}
</style>
</head>
<body>
<div class="btn-group">
<button type="button" class="btn btn-info btn-md">Books</button>
<button type="button" class="btn btn-info dropdown-toggle btn-md" data-toggle="dropdown">
<span class="caret"></span>
<span class="sr-only">Toggle Dropdown</span>
</button>
<ul class="dropdown-menu" role="menu">
<li>
<a href="#">HTML</a>
</li>
<li>
<a href="#">CSS</a>
</li>
<li class="divider"></li>
<li>
<a href="#">Show all</a>
</li>