[BulkActions] Not appearing on IndexTable small screen examples in Storybook

[lgriffee]

Issue summary

BulkActions isn't showing in IndexTable small screen examples in Storybook (however it seems to be functioning correctly in production so seems like just an issue with our Storybook example).

The following code in BulkActions.scss is responsible for hiding it at a small screen size but I'm still not sure why there's a difference between Storybook and production...

Expected behavior

Clicking the "Select" button inside the IndexTable HeaderWrapper triggers the "Select" button to disappear and be replaced by BulkActions.

BulkActions-production.mp4

Actual behavior

Clicking the "Select" button inside the IndexTable HeaderWrapper triggers the "Select" button to disappear and is not replaced with anything.

BulkActions-storybook.mp4

Steps to reproduce the problem

1. Go to Simple small screen index table or Small screen IndexTable with all of its elements
2. Click the "Select" button.