SO main content before sidebars

HTML

<script src="http://netdna.bootstrapcdn.com/twitter-bootstrap/2.2.2/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="https://dl.dropbox.com/u/2665617/bootstrap/2013-02-12/bootstrap.css">
<div class="container">
    
    <div class="row">
        
           <div class="span9">
               <div class="row">
             <div class="span6 pull-right">main content</div>
                
              <div class="span3">left bar</div>
               </div><!-- end nested row -->
        </div><!-- end span9 -->
  
            <div class="span3">right bar</div>

        </div><!-- end parent row-->

    </div><!-- end container -->

CSS

.span6{
    background-color:pink;
}