Just a quick post to the codex entry relating to this topic:
Nothing to hard there on the surface, but may require including the whole theme style which may break the editor visually requiring overriding some of the core theme elements, Which if it breaks or messes up the editor visually having to manually over write/nullify the offending css rules.
Leading to if that is the case is it maybe more efficient to create a separate css file for lists/paragraph/heading/image/video type defines ONLY compared to pulling in the whole theme style.. All that seems to be a revolving door mostly resting on the choice of using @import or not which has slightly higher overhead compared to not using it.
Literally the only difference would be not using @import, and instead of going round the merry go round just doing the work in the opposite direction instead of re-defining what we re-defined (the merry go round!), simply dig out what is needed and include that only.