Motorroad rendering in slippy map

Hi, where or how should I suggest changing the default OSM slippy map rendering style for roads with tag “motorroad=yes”.

In my opinion, there is a very big difference between a motorroad and a trunk, and in the slippy map you can’t note it. In JOSM they are rendered with a blue outline.

The best but most complicaterd way would be to open an issue in the Github-repository of the rendering style:
https://github.com/gravitystorm/openstreetmap-carto