Chord Quiz: Learn Piano Chord

Chord quiz application to learn chord names and chord component notes.
You can also search chords by chord name or constituent notes.

Functions/Features
- Chord name quiz (select minor, sevens, etc. with buttons)
- Chord component note quiz (select notes on piano keyboard)
- Up to 357 chord questions (21 root notes x 17 chord types)
- Chord sound playback
- Chord search (search by chord name or component notes)
- Chord detail page (check chord type, component notes, inversion form)
- Quiz settings (time limit, waiting time, number of questions, root note of question, chord of question, inversion form, keyboard order)
- Customization (dark mode, theme color)
- Simple design compliant with Material Design

Recent changes:
- Added the ability to change the order of keys in the chord sound quiz
- Fixed an issue where G#/Ab was incorrectly displayed as G#/Bb in the chord list
- Fixed the system on the purchase page
- Other UI changes and performance improvements