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(function fixedSidebar(){

var 
  $sidebar = $("#help-box"),
  $window = $(window),
    offset = $sidebar.offset(),
    topPadding = $(".site-header").outerHeight() + 20;

    $window.on("scroll resize", function() {			

      var parentWidth = $sidebar.parent().width();
      if($window.scrollTop() > offset.top - topPadding){
        $("body").addClass("fixed-sidebar");
        $sidebar.css({"top":topPadding, "width":parentWidth});
      } else {
        $("body").removeClass("fixed-sidebar");
        $sidebar.css("top", "auto");
      }

    });

})();