I really like Codemirror, it was simple to get set up in https://storytel.la/ https://storytel.la/ and easy to extend. I'm a few versions behind and didn't real

I really like Codemirror, it was simple to get set up in https://storytel.la/ https://storytel.la/ and easy to extend. I'm a few versions behind and didn't realise it handles mixed width fonts, so thanks for mentioning it.