This leaves the rest of the Tinychat UI untouched, just scroll up to see it.

Technically it's fullpage rather than fullscreen, so my title is slightly misleading. However, all you have to do for actual fullscreen is use your browser's built-in fullscreen functionality (the F11 key on most browsers).

I often go long periods of time without using Tinychat so don't hesitate to tell me in the Feedback if this needs to be updated.