Maperitive ruleset that's kept current with OSM-carto?

Thanks. I just tried it. It appears to be using Maperitive, just much more slowly & with a ruleset file even less like the current OSM-carto rendering. It also excludes recreation grounds.

I doubt very much that bbbike is using Maperitive (just alone practical concerns would rule that out), instead they are likely using the SVG backgend to mapnik, see https://github.com/mapnik/mapnik/wiki/MapnikRenderers just as we do on openstreetmap.org

You could naturally do this yourself and simply use the current openstreetmap-carto rules.

I assumed they're using Maperitive due to this header in the SVG. <title>Map Generated Using Maperitive (http://maperitive.net)</title>

I assume Cairo is what's used in 'Share' on OSM.org. This creates a file if 1.8mb when the equivalent from Maperitive is 35k! It converts text to lines (I think) & has no OSM relevant IDs to identify what the paths represent. I need to amend the SVG file directly to emphasise certain items.

What are the OSM-Carto files needed to attempt a conversions to Maperitive rules?

Maybe they are using maperitive but then you are, IMHO, never going to get nearer than a look-a-like style which is what you have been complaining about, see http://www.paulnorman.ca/blog/2015/11/openstreetmap-carto-complexity/ for why (the osm-corto style is located here https://github.com/gravitystorm/openstreetmap-carto )