do-demos

you commit inserts and deletes with ctrl+enter, and cancel them with ctrl+space (caret must be touching the green/red text)
color picker when holding ctrl+alt:
- ctrl+alt+arrow left/right: select color component
- ctrl+alt+arrow up/down: increment/decrement color component
- ctrl+alt+0-9: set color component to 0-9
- ctrl+alt+page up/down: increment/decrement all RGB components
change color of selected text with ctrl+p
doesn't work well on mobile yet (also many other bugs)