show_hide.js

$("#sections .panel.section").hide().first().show();
$("li.highlight a").click(function(event) {
  event.preventDefault();
  var target = $(event.currentTarget.getAttribute("href"));
  if (target.is(":visible")) return;
  $("#sections .panel.section:visible").children().fadeOut("fast", function(){
    $("#sections .panel.section").hide();
    target.show().children().fadeIn("fast");
  });
});