```ts
// YourPage.ts

import { LitElement, html } from 'lit-element';

@customElement('demo-document-screen')
class DocumentScreen extends LitElement {
  @property({ type: Object })
  data: {
    user: Record<string, unknown>;
    document: Record<string, unknown>;
    subdocuments: Array<Record<string, unknown>>;
  } = {};

  constructor() {
    super();
  }

  render() {
    const { user, document, subdocuments } = this.data;
    return html`
      <demo-page-layout .user=${user}>
        <demo-document-header .document=${document}></demo-document-header>
        <demo-document-list .documents=${subdocuments}></demo-document-list>
      </demo-page-layout>
    `;
  }
}

declare global {
  interface HTMLElementTagNameMap {
    'demo-document-screen': DocumentScreen;
  }
}
```