Observed Behaviour:
Given chat is enabled,
and given the browser window is less than 920 pixels wide,
and given the browser window is more than 786 pixels high,
when a user enables theatre mode,
then chat is shown below the stream,
and then there is no button to hide chat.

Expected Behaviour:
Given there is enough space vertically (currently 170px in addition to the stream player),
then there is a button to show/hide chat.