chromium/ash/webui/common/resources/cellular_setup/psim_flow_ui.html

<style>
  :host {
    display: flex;
    flex: 1 1 auto;
    flex-direction: column;
  }

  iron-pages {
    height: 400px;
  }
</style>
<iron-pages attr-for-selected="id"
    selected="[[selectedPsimPageName_]]"
    selected-item="{{selectedPage_}}">
  <setup-loading-page id="simDetectPage"
      loading-title="[[getLoadingTitle_(state_)]]"
      loading-message="[[getLoadingMessage_(state_)]]"
      is-sim-detect-error="[[isSimDetectError_(state_)]]">
  </setup-loading-page>
  <provisioning-page id="provisioningPage"
      delegate="[[delegate]]" show-error="{{showError_}}"
      cellular-metadata="[[cellularMetadata_]]"
      on-carrier-portal-loaded="onCarrierPortalLoaded_"
      on-carrier-portal-result="onCarrierPortalResult_">
  </provisioning-page>
  <final-page id="finalPage"
      delegate="[[delegate]]"
      show-error="[[showError_]]"
      message="[[i18n('pSimfinalPageMessage')]]"
      error-message="[[i18n('finalPageErrorMessage')]]">
  </final-page>
</iron-pages>