```js
// .storybook/preview.js

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

const customViewports = {
  kindleFire2: {
    name: 'Kindle Fire 2',
    styles: {
      width: '600px',
      height: '963px',
    },
  },
  kindleFireHD: {
    name: 'Kindle Fire HD',
    styles: {
      width: '533px',
      height: '801px',
    },
  },
};

export const parameters = {
  viewport: {
    viewports: {
       ...MINIMAL_VIEWPORTS,
      ...customViewports,
    },
  },
};
```