This is really interesting to me. I do a lot of mapping of natural surface single track trails (for hiking and mountain biking) along the way be sure to properly name things, add intersection markers, and create relations (routes and superroutes) to document the systems.

The biggest downside thus far is a good way of displaying the data. mtb.waymarkedtrails.org gets close, but I'd really like something that displays relations in the specified color, has sane intersection markers, etc.

I feel like there should be something out there which effectively lets me design a style sheet and then apply it to a map which I embed somewhere (maybe even in an app).

This... feels like it? Or if not this, can any of you recommend another system?

Ideally I'd love something I can self-host. I tried getting a copy of waymarkedtrails going and then modifying that, but it's a bit too specialized and I kept running into quirks getting the toolchain set up.

EDIT: Looks like this might not include the highway=path data that I need, much relations. Alas.