<div class="panel panel-primary">
  <div class="panel-heading">Panel heading without title</div>
  <div class="panel-body">
    Panel content
  </div>
</div>
<div class="panel panel-default"> 
  <div class="panel-heading">
    <h3 class="panel-title">Panel title</h3>
  </div>
  <div class="panel-body">
    Panel content
  </div>
</div>

Kết quả

<div class="panel panel-primary">...</div>
<div class="panel panel-success">...</div>
<div class="panel panel-info">...</div>
<div class="panel panel-warning">...</div>
<div class="panel panel-danger">...</div>