```md
<!-- MyComponent.stories.mdx -->

import { Meta, Story } from '@storybook/addon-docs';

import { INITIAL_VIEWPORTS } from '@storybook/addon-viewport';

<Meta
  title='Stories'
  parameters={{
    viewport: {
      viewports: INITIAL_VIEWPORTS,
      defaultViewport: 'iphone6'
    },
  }}
/>

<Story
  name='MyStory'
  parameters={{
    viewport: {
      defaultViewport: 'iphonex'
    }
  }}>
  {() => {
    return {
      template: `<div/>`,
    };
  }}
</Story>
```