Better YouTube Theatre Mode wót Sebbev

Improves YouTube's theater mode by making use of all of the available height.

How it works:
- Adds a very simple change that forces theater mode to expand vertically.

Enjoy a better viewing experience.


Source: https://github.com/Sebbev/better-youtube-theatre-mode
Original Chrome source: https://github.com/SimenMH/better-youtube-theatre-mode