Thanks for the help, but I got stuck with the height:100%. I tried it and couldn’t get to work.
So I created a module that is using flex grid instead and made the module responsive.
So, now the user can add as many cards that they want and the module then distributes these on one more many rows and columns depending on parameters they can set themselves. Pretty flexible. And they all align 
Sharing the code below.
The module
<div class="brv-card-container" style="grid-gap: {{ module.grid_gap}}px; grid-template-columns: repeat(auto-fit, minmax({{ module.min_column_width}}px, 1fr)); grid-auto-rows: minmax({{ module.min_row_height}}px, 1fr);">
{% for card in module.cards %}
<div style="background: {{module.background_color.color }}; padding: {{ module.card_padding }}px" class="brv-card {{ module.card_shadow }} ">
<div>{{ card.card_text }}</div>
</div>
{% endfor %}
</div>
The CSS
.brv-card-container {
display: grid;
}
.card-shadow {
box-shadow: 0px 3px 15px rgb(17 30 55 / 12%);
}
The JSON for the fields
[{“type”:“group”,“id”:“fa0d973a-0048-cbc9-fd55-c98a1d7d86b0”,“label”:“Cards”,“children”:[{“type”:“richtext”,“id”:“7227938f-8c69-272e-1f4a-779f5e9363e7”,“label”:“Card text”,“name”:“card_text”,“default”:“<p>Text</p>”}],“name”:“cards”,“default”:[{“card_text”:“<p>Text</p>”}],“occurrence”:{“min”:1,“max”:10,“default”:1,“sorting_label_field”:“c67e2970-0245-92b9-03c6-33ef83c31f1a”}},{“default”:500,“display”:“text”,“id”:“47792026-ebee-2112-eacf-45578358c602”,“label”:“Min Column width”,“locked”:false,“name”:“min_column_width”,“required”:false,“step”:1,“suffix”:“px”,“type”:“number”},{“default”:350,“display”:“text”,“id”:“c24ae3d3-4a3d-bffa-d8a8-fcf7199a132a”,“label”:“Min Row height”,“locked”:false,“name”:“min_row_height”,“required”:false,“step”:1,“suffix”:“px”,“type”:“number”},{“default”:30,“display”:“text”,“id”:“5932ba7e-48fe-83a3-d907-5ed2d9e76f3d”,“label”:“Grid Gap”,“locked”:false,“name”:“grid_gap”,“required”:false,“step”:1,“suffix”:“px”,“type”:“number”},{“type”:“color”,“id”:“20ac6b58-80c1-7a4a-450b-548c3fe480ed”,“default”:{“color”:“#f7f7f7”,“opacity”:100},“label”:“Background Color”,“name”:“background_color”},{“type”:“choice”,“id”:“80c59eb9-2fa3-bcfa-398b-12cbc48f0007”,“display”:“select”,“choices”:[[“card-shadow”,“Use shadow”],[" ",“No shadow”]],“label”:“Card Shadow”,“name”:“card_shadow”},{“type”:“number”,“id”:“304064b6-5f35-91ad-05c7-dc586f444a71”,“display”:“text”,“step”:1,“label”:“Card padding”,“name”:“card_padding”,“suffix”:“px”,“min”:0,“max”:100,“default”:40}]
**
**
I hope this helps someone else. It works for me anyway 
Cheers,
Pingo