Home page - Top app bar scroll behaviour

[niall-rb]

Description
At the top of the home page we should have a top bar that consists of:

• The page name (Badger events)
• The tabs that separate events by time (Today / Upcoming)
• The filter button that lets a user filter events by interest

To maximise screen space these elements should disappear when the user scrolls down but reappear when the user scrolls up again.

Acceptance criteria
GIVEN A user navigates to the home page
AND there are enough events to require the screen to scroll to view them all
WHEN The user scrolls down
THEN The top bar is invisible

GIVEN A user navigates to the home page
AND there are enough events to require the screen to scroll to view them all
WHEN The user scrolls up
THEN The top bar is visible again

Non-functional requirements
The design should match those provided in Badger Me App

Linked issues
Top App Bar