SO fixed button group

SO fixed button group

HTML

<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.2.2/css/bootstrap-combined.min.css">
<script src="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.2.2/js/bootstrap.min.js"></script>
<div class="container">
  <div class="row-fluid">
  <div class="span12">
    
  <div class="btn-group affix-top"  data-spy="affix" data-offset-top="10">
  <button class="btn">1</button>
  <button class="btn">2</button>
  <button class="btn">3</button>
  <button class="btn">4</button>
  <button class="btn">5</button>
  <button class="btn">6</button>
    <button class="btn">1</button>
  <button class="btn">2</button>
  <button class="btn">3</button>
  <button class="btn">4</button>
  <button class="btn">5</button>
  <button class="btn">6</button>
</div> <!-- end btn-group -->
    
    <div class="stuff"> content here - scroll to see affixed action</div>
    <div class="stuff"> content here</div>
    <div class="stuff"> content here</div>
    </div><!-- end span12 -->
    
  </div><!--end row-fluid -->
</div><!-- end container -->

CSS

.stuff{
  margin-top:20px;
  height:300px;
  width:300px;
  background-color:olive;
}