AngularJS Set a CSS class when a field is invalid

First Page

<!DOCTYPE html>
<html>
   <script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.6.9/angular.min.js">
   </script>
   <style>
      input.ng-invalid {
         background-color: blue;
     }
   </style>
   <body>
      <form ng-app="" name="myForm">
         Enter your name:
         <input name="myName" ng-model="myText" required>
      </form>
      <p>Edit the text field and it will get/lose classes
      according to the status.</p>
   </body>
</html>

Output

First Page