storybook/docs/snippets/web-components/my-component-story-configure-viewports.js.mdx

```js
// my-component.stories.js

import { MyComponent } from'./my-component';

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

export default {
  /* 👇 The title prop is optional.
   * See https://storybook.js.org/docs/7.0/web-components/configure/overview#configure-story-loading
   * to learn how to generate automatic titles
   */
  title: 'MyComponent',
  parameters: {
    //👇 The viewports object from the Essentials addon
    viewport: {
      //👇 The viewports you want to use
      viewports: INITIAL_VIEWPORTS,
      //👇 Your own default viewport
      defaultViewport: 'iphone6'
    },
  };
};

/*
 *👇 Render functions are a framework specific feature to allow you control on how the component renders.
 * See https://storybook.js.org/docs/7.0/web-components/api/csf
 * to learn how to use render functions.
 */
export const InitialButton = {
  render: () => MyComponent(),
  parameters: {
    viewport: {
      defaultViewport: 'iphonex'
    },
  },
};
```