Hide headerbar in fullscreen mode

[muhdsalm]

Please submit only one feature request in one issue!
When I want to use this app in fullscreen to present on screenshare, the header bar being visible looks less aesthetic. It would look better if the headbar was not visible in fullscreen mode

Is your feature request related to a problem? Please describe.
The problem is that the header bar is visible when the app is fullscreen, which looks bad when screen sharing/recording.

Describe the solution you'd like
For the headerbar to not be visible during fullscreen.

Describe alternatives you've considered
This could be an optional setting.

Additional context
Add any other context or screenshots about the feature request here.