Как использовать ng-стиль с div: after?

angular.module('app', []);

.box {
  height: 150px;
  width: 200px;
  overflow: hidden;
  position: relative;
  background: tomato;
}

.box-xtra::after {
  content: "div2";
  width: 100px;
  height: 20px;
  position: absolute;
  top: 10px;
  left: -30px;
  transform: rotate(-45deg);
  background-color: white;
  text-align: center;
}

<script src = "https://ajax.googleapis.com/ajax/libs/angularjs/1.7.2/angular.min.js"></script>
<div ng-app = "app">
  <div style = "margin-bottom: 10px;">
    <label>Show div2 <input type = "checkbox" ng-model = "ctrl.shouldShowDiv2" /></label>
  </div>
  <div class = "box" ng-class = "{'box-xtra': ctrl.shouldShowDiv2}"></div>
</div>