js/90-mobilenav.js

   1 $(function(){
   2         if(window.innerWidth >= 768)
   3                 return;
   4         $('#title')[0].insertAdjacentHTML('beforebegin', '<div class="text-center">Tap title to toggle menu</div>');
   5         $('nav')[0].classList.add('hidden');
   6         $('#title').on('click', () => $('nav')[0].classList.toggle('hidden'));
   7 });