Ah cool! Now it works, sorry from my side (if that was somewhere in the readme - or the code I did not see it)
Yes it works! (Nice that you have already made this tag transparent).
I am wondering if you know something like a hotkey to add this tag to all children blocks (and how to remove it as well?)
This could be a plug-in as well (slash-command to add or remove #.side to each block below)