Vaadin Flow – a marvelous deer

// Determine new class
class LikeableElement extends PolymerElement {

  // Here will be the component’s public features
  static get properties() { return { liked: Boolean }}

  // That’s how the DOM tree will look inside, CSS influences only the component itself
  static get template() {
    return html`
      <style>
        .response { margin-top: 10px; }
      </style>
      <paper-checkbox checked="">I like web components.</paper-checkbox>

      <div hidden$="[[!liked]]" class="response">Web components like you, too.</div>
    `;
  }
}