text: function hamburger() {
      document.getElementById('line1').classList.toggle('line_1');
      document.getElementById('line2').classList.toggle('line_2');
      document.getElementById('line3').classList.toggle('line_3');
      document.getElementById('nav').classList.toggle('in');
  }
  document.getElementById('hamburger').addEventListener('click', function () {
      hamburger();
  });