There is some code of angular 2 code. It can't pass w3c validation because of the tag . Or angular library somehow changes the source in the end to make it valid?
<!DOCTYPE html>
<html>
  <head>
    <title>Angular 2 QuickStart</title>
    ...
  </head>
  <!-- 3. Display the application -->
  <body>
    <my-app>Loading...</my-app>
  </body>
</html>
