Hi,
Damn, I forgot that I had an unsolved problem with npm on this computer (which has nothing to do with your plugin). When do you plan to publish it in the repo?
For CSS, I don't know much about it unfortunately but maybe others who experiment with CSS in Joplin will be interested (@Nacandev - @BeatLink - @andrejilderda).
For the features, what you describe is already very good. In the same way, one could imagine to display the "tags" of the note as backlinks context. In a Zettlekasten-like approach this would be very practical. Same for datation informations. Moreover, I'm using more and more todo in Joplin and I would like to be able to exclude completed todo from backlinks. I want to say in an automatic way and not only by having to add one by one these to the list of ignored files.
Anyway, it's really a very interesting plugin proposal you're making here!