Styling Polymer Templates

import { PolymerElement } from '@polymer/polymer/polymer-element.js';
import { html } from '@polymer/polymer/lib/utils/html-tag.js';

class MyView extends PolymerElement {
  static get template() {
    return html`
      <style>
        :host {
          /* Styles for the <my-view> host element */
          display: block;
        }

        .my-view-title {
          font-weight: bold;
          border-bottom: 1px solid gray;
        }
      </style>
      <h2 class="my-view-title">My view title</h2>
    `;
  }

  static get is() {
    return 'my-view';
  }
}
customElements.define(MyView.is, MyView);