various fixes

private/js/modules/notifications.js

@@ -1,8 +1,20 @@
 $(function() {
   var $body = $('body');
 
+  var cookie_name = 'last_notification_update';
+  var last_notification = getCookie(cookie_name);
+
+  var $header_button_notification = $('.header__button--notification');
+  var current_notification = $header_button_notification.attr('data-updated');
+
+  if (last_notification !== current_notification) {
+    $header_button_notification.addClass('new');
+  }
+
   $body.on('click', '.header__button--notification', function(event) {
     event.preventDefault();
+    setCookie(cookie_name, current_notification, 90);
+    $(this).removeClass('new');
     $body.toggleClass('notification_open');
   });