title: Replicating Bootstraps main nav and subnav
body: <p>I need to quickly knock up the functionality of the twitter bootstraps main navigation and sub navigation e.g. <a href="http://twitter.github.com/bootstrap/scaffolding.html" rel="noreferrer">http://twitter.github.com/bootstrap/scaffolding.html</a> (when you scroll the subnav becomes fixed to that main navigation)</p>
  
  <p>Has anyone implemented this or are there any tutorials?</p>