In the 2018 State of Email Report, pg. 12 under Action Items, it mentions making an email responsive by triggering the change "based on where that design breaks instead of specific screen sizes." We do currently trigger changes based on a specific width. But I am trying to understand what "where that design breaks" means. Does the trigger need to be when the width of the device screen is smaller than the initial width of the email layout? What would that CSS/Media Query look like?