old_contents: window.addEventListener('load', function() {
      (function() {
          var headerEle = document.getElementById('page-header');
  
          function toggleNavStyle() {
              var scrollTop = window.pageYOffset || document.body.scrollTop || document.documentElement.scrollTop;
  
              headerEle.classList[ scrollTop > 30 ? 'add' : 'remove' ]('page__header--small');
          }
  
          headerEle && document.addEventListener('scroll', toggleNavStyle);
      })();
      
      (function() {
          var 
              btn = document.querySelector('button.page__menu-btn'),
              menu = document.querySelector('nav.page__nav');
  
          if (btn && menu) {
              var packMenu = new Pack(menu);
  
              packMenu.base('js-open').transfrom('page__nav--open');
  
              btn.addEventListener('click', function() {
                  packMenu.toggle();
              });
          }
      })();
  
      (function() {
          var 
              header = document.getElementById('page-header')
              title = header.querySelector('.info__title'),
              desc = header.querySelector('.info__desc');
  
          title && new Pack(title)
              .animation('js-animation')
              .end(function() {
                  var arr = ['js-animation'];
  
                  arr.forEach(function(item) {
                      title.classList.remove(item);
                  });
              })
              .toggle();
  
          desc && new Pack(desc)
              .base('js-ease-out-leave-active')
              .base('js-ease-out-leave')
              .transfrom('js-ease-out-enter-active')
              .end(function() {
                  var arr = ['js-ease-out-enter', 'js-ease-out-enter-active', 'js-ease-out-leave', 'js-ease-out-leave-active'];
  
                  arr.forEach(function(item) {
                      desc.classList.remove(item);
                  });
              })
              .toggle();
      })();
  });
new_contents: window.addEventListener('load', function() {
      (function() {
          var headerEle = document.getElementById('page-header');
  
          function toggleNavStyle() {
              var scrollTop = window.pageYOffset || document.body.scrollTop || document.documentElement.scrollTop;
  
              headerEle.classList[ scrollTop > 30 ? 'add' : 'remove' ]('page__header--small');
          }
  
          headerEle && document.addEventListener('scroll', toggleNavStyle);
      })();
      
      (function() {
          var 
              btn = document.querySelector('button.page__menu-btn'),
              menu = document.querySelector('nav.page__nav');
  
          if (btn && menu) {
              var packMenu = new Pack(menu);
  
              packMenu.base('js-open').transfrom('page__nav--open');
  
              btn.addEventListener('click', function() {
                  packMenu.toggle();
              });
          }
      })();
  
      (function() {
          var header = document.getElementById('page-header');
          
          if (!header) return;
  
          var
              title = header.querySelector('.info__title'),
              desc = header.querySelector('.info__desc');
  
          title && new Pack(title)
              .animation('js-animation')
              .end(function() {
                  var arr = ['js-animation'];
  
                  arr.forEach(function(item) {
                      title.classList.remove(item);
                  });
              })
              .toggle();
  
          desc && new Pack(desc)
              .base('js-ease-out-leave-active')
              .base('js-ease-out-leave')
              .transfrom('js-ease-out-enter-active')
              .end(function() {
                  var arr = ['js-ease-out-enter', 'js-ease-out-enter-active', 'js-ease-out-leave', 'js-ease-out-leave-active'];
  
                  arr.forEach(function(item) {
                      desc.classList.remove(item);
                  });
              })
              .toggle();
      })();
  });
subject: fix header js bug