Custom Trail Router map background

[westis]

This one would be really cool, but obviously not of highest priority. But imagine a custom map background where features that Trail Router is using in its route calculation are better displayed? I'm thinking of different renderings based on surface, smoothness, width, trail_visibility, mtb:scale, sac_scale etc.

Needs some good thinking though, to make it logical to the user. But to separate smaller trail paths from wider and smoother ones. The current map background does some rendering based on mtb:scale for example. But there's no link to a map index where this is explained. What is the Mapbox map background being used? Perhaps it's something that can quite easily be fine-tuned in Mapbox Studio?

Linked to #14 but that issue is about giving the user multiple background options.