It seems like the bootstrap panel class is not being applied in this code snippet:
<div class="container main-content">
<div class="row">
<div class="col-sm-3">
<div class="panel panel-primary">
<div class="panel-heading">
<img src="http://cliparts.co/cliparts/8TE/6jz/8TE6jzq9c.png" class="stats-image" />
<h3>ACHIEVERS</h3>
</div>
<div class="panel-body stats-body">
<span class="stats-value">37%</span>
</div>
</div>
</div>
</div>
</div>
Check out the Plnkr link for the full code: http://plnkr.co/edit/7e3mXCDixuJ4U06lu3TX?p=info
Can you spot the issue here ?