Stacks without margins

Hi,
For my smart switches and tablets interfaces, I use stack-in-cards a lot to display buttons or information without any margin.
Until a while ago it worked fine, but since an update to Home Assistant a few weeks ago, margins have appeared and I can’t seem to remove them.

I’ll take as an example the interface on one of my smart switches, which has in-line On/Off/Auto buttons on the right and in-line Air/Water/pH/RedOX info at the bottom.
Here it is before the update:
Capture d'écran 2024-05-13 184621
And after the update:
Capture d'écran 2024-05-13 184643
This is exactly the same code at the same time taken from my production HA (with the current update) and my testing HA (which hadn’t been updated since January).
However, I can’t remember the version number of my testing HA because to test it I updated it and it added the margins to the test version without any change to the code.

Here is the code:

type: custom:vertical-stack-in-card
cards:
  - type: horizontal-stack
    cards:
      - type: custom:mini-graph-card
        name: Air
        hour24: true
        smoothing: true
        decimals: 1
        font_size: 72
        animate: true
        show:
          labels: false
          points: false
          legend: false
          fill: fade
        entities:
          - entity: sensor.thermometre_plage_temperature
            color: orange
        card_mod:
          style: |
            ha-card {
              border-right: 1px solid var(--ha-card-border-color) !important;
            }
      - type: custom:mini-graph-card
        name: Eau
        icon: mdi:water
        hour24: true
        smoothing: true
        decimals: 1
        font_size: 72
        animate: true
        show:
          labels: false
          points: false
          legend: false
          fill: fade
        entities:
          - entity: sensor.sonde_piscine_temperature
        card_mod:
          style: |
            ha-card {
              border-right: 1px solid var(--ha-card-border-color) !important;
            }
      - type: custom:mini-graph-card
        name: pH
        icon: mdi:test-tube
        hour24: true
        smoothing: true
        decimals: 1
        font_size: 72
        animate: true
        show:
          labels: false
          points: false
          legend: false
          fill: fade
        entities:
          - entity: sensor.oklyn_ph
            color: green
        lower_bound: 5
        upper_bound: 8
        card_mod:
          style: |
            ha-card {
              border-right: 1px solid var(--ha-card-border-color) !important;
            }
      - type: custom:mini-graph-card
        name: RedOx
        icon: mdi:bacteria
        hour24: true
        smoothing: true
        decimals: 1
        font_size: 72
        animate: true
        show:
          labels: false
          points: false
          legend: false
          fill: fade
        lower_bound: 50
        upper_bound: 800
        entities:
          - entity: sensor.oklyn_redox
            color: violet

Same thing here. Before the update it was like that:
Capture d'écran 2024-05-13 214019
Now it is like that:
Capture d'écran 2024-05-13 213909

In fact, I remember that I obtained this by wrapping my code by a custom:vertical-stack-in-card even if it has only one card. But as of today it is not effective anymore…

Do you know how I can get this back, i.e. a stack in without any margin? I’ve tried margin: 0px, but it doesn’t work…

same