- The exercises in focus mode feel too short, maybe they could get longer over time?
- Disable text selection within the lesson container (using `user-select: none`). Not strictly necessary, but right now I can just Ctrl+C / Ctrl+V and hit 1000 WPM, which is pretty amusing.
- After completing an exercise, allow advancing to the next one via keyboard (Space or Enter). At the moment, the player has to take their hand off the keyboard, grab the mouse, and click "Next Exercise." For a game about focus, it kind of breaks the flow.