metadata-aware themes

[arnavs]

I've been trying to use cell metadata to implement custom CSS in a JupyterHub theme.

The thing is, it doesn't seem that metadata maps cleanly to something like an HTML div or span class, and existing themes (e.g., like jupyterhub-light-theme) aren't metadata aware.

There are existing git issues on this subject (e.g., here), but I don't think they've gotten much traction.