> Create a single self-contained index.html: a ~2-minute animated piano performance in a hand-drawn crayon style.
> Scene: a cozy room at night, an upright piano, a small black cat playing it. Crayon texture on every surface: grainy strokes,wobbly outlines, paper tooth.
> Music: compose an original piano piece (~40 bars, clear melody, calm then building, soft ending). Synthesize the piano in Web Audio with harmonics, hammer noise and reverb. No audio files.
> Sync: one timeline drives both. The cat's paws hit the keys that are actually sounding. Lights, camera and mood follow the music.
> Rules: Canvas 2D only, no libraries, no external assets. Support pause/replay and ?t=90 to jump to any moment.