```js
// MyComponent.stories.js

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

import MyComponent from './MyComponent.svelte';

export default {
  /* 👇 The title prop is optional.
  * See https://storybook.js.org/docs/svelte/configure/overview#configure-story-loading
  * to learn how to generate automatic titles
  */
  title: 'MyComponent',
  component: 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',
    },
  },
};

export const MyStory = () => ({
  Component: MyComponent,
});
MyStory.parameters = {
  viewport: {
    defaultViewport: 'iphonex',
  },
};
```