text of warning / note directives should be rendered in a box or/and in another color.

Currently it looks like this:

note

This is a note

but it should look somehow like here -->

see also -->
https://sublime-and-sphinx-guide.readthedocs.io/en/latest/notes_warnings.html

IMHO this would be a big improvement for the readability of technical documentation with less effort for you for the implementation.