```ts
// Page.stories.ts

import { Page } from './page.component';

export default {
  component: Page,
};

export const CustomFooter = {
  args: {
    footer: 'Built with Storybook',
  },
  render: (args) => ({
    props: args,
    template: `
      <storybook-page>
        <ng-container footer>${args.footer}</ng-container>
      </storybook-page>`,
  }),
};
```