bug: "cards" don't have same height

[davidsneighbour]

this one will be a bit more invasive. cards (post preview in lists like the recent posts on the homepage, blog list pages, etc) do not have the same height when next to each other and having differing content.

Issue here is, that currently they are build via col classes that can run over multiple rows. We need to re-write that into flex rows that contain x posts (depending on the view) that we could force to stretch and then lay out properly. That will lead to issues with dynamic width column counts.

On the other side, we know the height of image --- headline (max 2 lines) --- content preview (max-3 lines) --- read more button. That might be solvable via min-height, but could look ugly on a 1 per row layout in sm/xs.