that margin-top: 0px !important was a desperate attempt to get rid of the margin, and indeed it was misplaced So I moved it up to the card-content and now it respected.
That is a bit PITA that this margin-top: auto somehow generates way to large margins seemingly not related to what size you size in the widget the grid layout.
That is a final code I used.
- component: f7-card-content
config:
style:
margin-top: 2% !important