text: import '@polymer/app-layout/app-header-layout/app-header-layout.js';
  import '@polymer/app-layout/app-header/app-header.js';
  import '@polymer/app-layout/app-toolbar/app-toolbar.js';
  import '@polymer/paper-icon-button/paper-icon-button.js';
  import { html } from '@polymer/polymer/lib/utils/html-tag.js';
  import { PolymerElement } from '@polymer/polymer/polymer-element.js';
  
  class HassSubpage extends PolymerElement {
    static get template() {
      return html`
      <style include="ha-style"></style>
      <app-header-layout has-scrolling-region="">
        <app-header slot="header" fixed="">
          <app-toolbar>
            <paper-icon-button icon="mdi:arrow-left" on-click="_backTapped"></paper-icon-button>
            <div main-title="">[[header]]</div>
          </app-toolbar>
        </app-header>
  
        <slot></slot>
      </app-header-layout>
  `;
    }
  
    static get properties() {
      return {
        header: String
      };
    }
  
    _backTapped() {
      history.back();
    }
  }
  
  customElements.define('hass-subpage', HassSubpage);
  