        var popupMessageTarget = document.querySelector('#popupMessageTarget');
            popupMessageTarget.textContent = 'Thanks for staying with us a bit longer.';
            popupMessageTarget.classList.remove("animatePopupMessage");
            popupMessageTarget.classList.add("animatePopupMessage");
          }
        });
      });
    });
  </script>
</head>
<body>
  <nav>
    <h1>Popup Example</h1>
    <button class='align-flush' id="openPopup">
      <label>Popup</label>
    </button>
  </nav>
