Redesign standard editor style

[danielsaidi]

I think it should be equally easy to create a full-blown text editor application, not only the editor itself. It should be a light, harmonic UI where every part (commands, sidebar, toolbars, etc.) have their own view modifier, like view styles.

It should be equally easy to create a "full screen" (or full view) editor app, as to create one that mimics having a "paper sheet" like apps like Word and Pages have, even though the model doesn't have a document size.

Take inspiration from this nice design by Jia, which is lighter and has more space than the macOS design currently provides: