@PitaJ I've got no experience with jQuery whatsoever. So I would very much appreciate it if you'd look into it. Thanks
Also I build my own NodeBB for Docker with custom plugins and stuff so a change in user.js would be no problem (just an sed command in my build script).
Threw something quick together based on nodebb-plugin-spoilers, I also looked into extending the existing markdown plugin using the extension support the parser has, but didn't really succeed. Would be great if we could just add markdown-it extensions in the admin panel to extend the syntax, cuz there are plenty existing ones