Numbering of notebook cells

[kolibril13]

Context

nbsphinx has great cell numbering, as can be seen in this screenshot.

Proposal

It would be amazing if there was an option for cell numbering for myst-nb rendered notebooks as well!

Looking at the above screenshot, it would be also interesting to discuss the vertical spacing and the background color of the output cells. In my opinion, it is easier to associate the cells and outputs with each other when they are close together.

Tasks and updates

No response