Overtone

Build **Overtone** — a small, delightful music-theory tool that helps someone see and hear how scales and chords are built. Pick a musical key and a scale (major, minor, and a few more interesting ones — dorian, pentatonic, blues, whatever you like), and the tool shows you the notes and lets you actually hear them. It should be interactive and correct: - A keyboard (piano-style, or another instrument layout if you prefer) that highlights the notes belonging to the chosen key and scale. - Controls to change the root note and the scale type, updating the highlighting live. - Real sound — clicking a note or a "play the scale" control produces the correct pitches. Synthesize the audio in the browser (the Web Audio API), so no audio files are needed. - Show the useful theory: the note names, the scale degrees, and ideally the diatonic chords that come from the scale — so a learner actually gains understanding, not just pretty colors. Get the music theory right: the intervals, the note names (including sharps/flats), and the pitches must be accurate. The register is playful, hands-on, and musical — a toy you can't stop poking, that also teaches. Build everything yourself; no external images or network libraries (Web Audio is fine and encouraged). This challenge stresses **interactive tools with real logic and audio** — correct domain modelling plus a joyful, tactile interface. All design decisions — instrument, layout, palette, which scales/features, sound design — are yours. There is no single right answer; make something with a point of view.