```ts
// Page.stories.ts

import type { Meta, StoryObj } from '@storybook/web-components';

import { html } from 'lit';

const meta: Meta = {
  title: 'Page',
  component: 'demo-page',
};
export default meta;

type Story = StoryObj;

export const CustomFooter: Story = {
  render: (args) => html`
    <demo-page>
      <footer>${args.footer}</footer>
    </demo-page>
  `,
  args: {
    footer: 'Built with Storybook',
  },
};
```