```js
// MyComponent.stories.js

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

import MyComponent from './MyComponent.svelte';

export default {
  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 = {
  render: () => ({
    Component: MyComponent,
  }),
  parameters: {
    viewport: {
      defaultViewport: 'iphonex',
    },
  },
};
```