(function(document) {
        var toggleDocumentationMenu = function() {
          var navBtn = document.querySelector('.main-nav__btn');
          var navList = document.querySelector('.main-nav__list');
          var navIsOpenedClass = 'nav-is-opened';
          var navListIsOpened = false;

          navBtn.addEventListener('click', function (event) {
            event.preventDefault();

            if (!navListIsOpened) {
              addClass(navList, navIsOpenedClass);
              navListIsOpened = true;
            } else {
              removeClass(navList, navIsOpenedClass);
              navListIsOpened = false;
            }
          });
        }

        var toggleMainNav = function() {
          var documentationItem =
              document.querySelector('.main-nav__item--documentation');
          var documentationLink =
              document.querySelector('.main-nav__item--documentation > .main-nav__link');
          var documentationIsOpenedClass = 'subnav-is-opened';
          var documentationIsOpened = false;

          documentationLink.addEventListener('click', function (event) {
            event.preventDefault();

            if (!documentationIsOpened) {
              documentationIsOpened = true;
              addClass(documentationItem, documentationIsOpenedClass);
            } else {
              documentationIsOpened = false;
              removeClass(documentationItem, documentationIsOpenedClass);
            }

          });
        }

        var isTouch = function() {
          return ('ontouchstart' in window) ||
            window.DocumentTouch && document instanceof DocumentTouch;
        };

        var addClass = function (element, className) {
          if (!element) { return; }
          element.className = element.className.replace(/\s+$/gi, '') + ' ' + className;
        }

        var removeClass = function(element, className) {
          if (!element) { return; }
          element.className = element.className.replace(className, '');
        }

        var html = document.querySelector('html');
        removeClass(html, 'no-js');
        addClass(html, 'js');

        if (isTouch()) {
          removeClass(html, 'no-touch');
          addClass(html, 'is-touch');
        }

        toggleDocumentationMenu();
        toggleMainNav();
      })(document);