Pluto specific MIME type for better support of dark/light mode?

[Roger-luo]

I noticed that dark mode has now been integrated in Pluto itself, however, from the package side, whether the visualization is in dark mode or not is unknown and thus the output will be assumed to show in light mode or just default.

I'm wondering if the runner can pick up a specific MIME type by checking whether the frontend is in dark mode or not so that as a package author we can provide visualization specific to dark modes via e.g MIME"application/pluto+png+dark" and MIME"application/pluto+png+light"?

I'm not sure how this can be done exactly so I think someone more familiar with the frontend may know how to do it.