$(document).ready(function () {
  var h = $('.full-page-jumbotron').height();
  $(window).on('wheel', function (e) {
    if ($(window).scrollTop() > 0) {
      $('.navbar-fixed nav').css('background', '#607d8b');
      $('.navbar-fixed nav *').css('text-shadow', 'none');
      $('.full-page-jumbotron *').slideUp();
      $('.full-page-jumbotron').height(h/2);
    } else {
      $('.navbar-fixed nav').css('background', 'transparent');
      $('.navbar-fixed nav *').css('text-shadow', '1px 1px black');
      $('.full-page-jumbotron *').fadeIn();
      $('.full-page-jumbotron').height(h);
    }
  });
});

@@ -91,12 +91,13 @@
 on('
-whee
+scrol
 l', 

fix #12, change event listener from wheel to scroll in dynamic_navbar.js