<link href="//netdna.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//netdna.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"></script>
<script src="//code.jquery.com/jquery-1.11.1.min.js"></script>
<div class="container">
<h2>Sách của bạn</h2>
<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="#lop12">
Lớp <span class="bg-round bg-lop12">1</span> và <span class="bg-round bg-lop12">2</span>
</a>
</h4>
</div>
<div id="lop12" class="panel-collapse collapse in">
<div class="panel-body">
<div class="col-xs-2 col-md-2">
<div class="caption">
<h4>Lớp 1</h4>
</div>
<a href="#" class="thumbnail">
<img src="http://s.sachmem.com/public//bookcovers/TA1_head.png" alt="Tiếng Anh 1">
</a>
</div>
<div class="col-xs-2 col-md-2">
<h4>Lớp 2</h4>
<a href="#" class="thumbnail">
<img src="http://s.sachmem.com/public//bookcovers/TA2_head.png" alt="Tiếng Anh 2">
</a>
</div>
</div>
</div>
</div>
<div class="panel panel-default">
