Update js/main.js, index.html

js/main.js

@@ -14,3 +14,17 @@ function gototop() {
   document.body.scrollTop = 0; // For Safari
   document.documentElement.scrollTop = 0; // For Chrome, Firefox, IE and Opera
 }
+
+document.addEventListener('DOMContentLoaded', function() {
+  const $navbarBurgers = Array.prototype.slice.call(document.querySelectorAll('.navbar-burger'), 0);
+  if ($navbarBurgers.length > 0) {
+    $navbarBurgers.forEach(function(el) {
+      el.addEventListener('click', function() {
+        const target = el.dataset.target;
+        const $target = document.getElementById(target);
+        el.classList.toggle('is-active');
+        $target.classList.toggle('is-active');
+      });
+    });
+  }
+});