<div class="panel panel-default">   
    <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>