var nav = document.querySelector('.nav');
var toggle = document.querySelector('.hamburger');
var navItems = nav.querySelectorAll('.menu');

toggle.addEventListener('click', toggleNav);

function toggleNav() {
  
  // Show Nav
  nav.classList.toggle('active');
  
  // Transform Hamburger into 'X'
  toggle.classList.toggle('active');
  
  // Show Nav Items
  for (var i = 0, ii = navItems.length; i < ii; i++) {
    navItems[i].classList.toggle('active');
  }
}