text: //Get the button:
  mybutton = document.getElementById("myBtn");
  
  // When the user scrolls down 20px from the top of the document, show the button
  window.onscroll = function() {scrollFunction()};
  
  function scrollFunction() {
    if (document.body.scrollTop > 20 || document.documentElement.scrollTop > 20) {
      mybutton.style.display = "block";
    } else {
      mybutton.style.display = "none";
    }
  }
  
  // When the user clicks on the button, scroll to the top of the document
  function topFunction() {
    document.body.scrollTop = 0; // For Safari
    document.documentElement.scrollTop = 0; // For Chrome, Firefox, IE and Opera
  }
  
  
  
  /* Open when someone clicks on the span element */
  function openNav() {
      document.getElementById("myNav").style.width = "100%";
    }
    
    /* Close when someone clicks on the "x" symbol inside the overlay */
    function closeNav() {
      document.getElementById("myNav").style.width = "0%";
    }