text: ;(function (window, document, undefined) {
    var $tocNav = document.querySelector('.toc-nav'),
        $tocNavMenu = document.querySelector('#tocNavMenu'),
        $menuLink = document.querySelector('#tocNavMenu .menu-link a');
        $buttonShowToc = document.querySelector('#buttonShowToc'),
        $header = document.querySelector('.header'),
        $navigation = document.querySelector('.navigation'),
        topHeight = $header.clientHeight + $navigation.clientHeight,
        windowHeight = window.innerHeight;
  
    // paralax on header
    $('.header').stellar();
  
    if ($buttonShowToc) {
      $tocNavMenu.addEventListener('click', function (event) {
        var menuAnchor = event.target.getAttribute('href'),
            anchorOffset = $(menuAnchor).offset();
  
        $('html, body').animate({
          scrollTop: anchorOffset.top
        }, 500);
  
        event.preventDefault();
      });
  
      $buttonShowToc.addEventListener('click', function (event) {
        event.preventDefault();
  
        if (!$tocNav.classList.contains('is-visible')) {
          $tocNav.classList.remove('is-hidden');
          $tocNav.classList.add('is-visible');
        }
        else {
          $tocNav.classList.remove('is-visible');
          $tocNav.classList.add('is-hidden');
        }
      });
  
      window.addEventListener('scroll', function (event) {
        var scrollY = this.scrollY;
  
        if (scrollY >= topHeight) {
          $tocNav.classList.add('is-fixed')
        }
        else if (scrollY <= topHeight && $tocNav.classList.contains('is-fixed')) {
          $tocNav.classList.remove('is-fixed');
        }
      });
    }
  })(window, document);
  