AMB: The Ancient Machine Book Format
amb.osdn.io
amb.osdn.io
It is actually very well thought out for authoring on old machines, not just for rendering/reading.
See https://man.archlinux.org/ for how you can make man-pages look real nice when converted to html.
I like that the man system is frontend agnostic tho - I don't want to deal with remote desktop when sshed into a server.
This AMB thing isn't better than man pages.