Replicating Bootstraps main nav and subnav

Question

I need to quickly knock up the functionality of the twitter bootstraps main navigation and sub navigation e.g. http://twitter.github.com/bootstrap/scaffolding.html (when you

Answer 1

Here is another code

$(function(){
  var
    $win = $(window),
    $filter = $('.navbar'),
    $filterSpacer = $('
', {
      "class": "filter-drop-spacer",
      "height": $filter.outerHeight()
    });
  $win.scroll(function(){     
    if(!$filter.hasClass('navbar-fixed-top')){
        if($win.scrollTop() > $filter.offset().top){
        $filter.before($filterSpacer);
        $filter.addClass("navbar-fixed-top");
      }
    }else if ($filter.hasClass('navbar-fixed-top')){
      if($win.scrollTop() < $filterSpacer.offset().top){
      $filter.removeClass("navbar-fixed-top");
      $filterSpacer.remove();
    }
    } 
  });
});