'use strict';

(function() {
  var nav = document.getElementById('site-navigation'), button, menu;
  button = nav.getElementsByTagName('button')[0];
  menu = nav.getElementsByTagName('ul')[0];

  // Hide the menu if it's empty
  if (! menu.childNodes.length) {
    button.style.display = 'none';
  }

  button.onclick = function() {
    if (button.className.indexOf('toggled-on') !== -1) {
      button.className = button.className.replace(' toggled-on', '');
      menu.className = menu.className.replace(' toggled-on', '');
    } else {
      button.className += ' toggled-on';
      menu.className += ' toggled-on';
    }
  };
})();

'use strict';

function parallax() {
  var scrolled = $(window).scrollTop();
  if (scrolled < 500) {
    $('.blog-header').css('background-position', '0px ' + (0.2 * scrolled) + 'px');
  }
}
$(window).scroll(parallax);

(function() {
  var nav = document.getElementById('site-navigation'), button, menu;
  button = nav.getElementsByTagName('button')[0];
  menu = nav.getElementsByTagName('ul')[0];

  // Hide the menu if it's empty
  if (! menu.childNodes.length) {
    button.style.display = 'none';
  }

  button.onclick = function() {
    if (button.className.indexOf('toggled-on') !== -1) {
      button.className = button.className.replace(' toggled-on', '');
      menu.className = menu.className.replace(' toggled-on', '');
    } else {
      button.className += ' toggled-on';
      menu.className += ' toggled-on';
    }
  };
})();

--- 
+++ 
@@ -1,4 +1,12 @@
 'use strict';
+
+function parallax() {
+  var scrolled = $(window).scrollTop();
+  if (scrolled < 500) {
+    $('.blog-header').css('background-position', '0px ' + (0.2 * scrolled) + 'px');
+  }
+}
+$(window).scroll(parallax);
 
 (function() {
   var nav = document.getElementById('site-navigation'), button, menu;
Delete unused parallax scrolling js code
