Listening to classical pieces with the score was one of my favourite things to do when I was at music school. One thing that would be cool would be an overlay

Listening to classical pieces with the score was one of my favourite things to do when I was at music school. One thing that would be cool would be an overlay of the clef, time signature and current (declared hah) key on the left hand side that updated as everything changed. Good for context as you're following along. Super nice work though.