I started learning the guitar years ago, but lost motivation once I got into university. Maybe I'll give it another shot and use this as a refresher on the theory!

Anyway, one small nitpick on the website: When on German language the word "FUNKTIONSHIGHLIGHTS" overflows on mobile. I would replace it with "WICHTIGSTE FUNKTIONEN" as that is two words.

Good luck, the website and App look nice!