Entity filter, card-mod background [solved]

Dear all. I don’t manage to understand this even though I read a previous thread, sorry.
I want a entity filter to show a card when something is wrong. Have a bunch of sensors indicating a alarm or fault. However I want a red or distinct background so that it really pops.

I tried to set a border with card-mod, but that unfortunately still shows a color line when the card is hidden. I managed to set a background, but this just shows a red rectangle, and I don’t see the entities. What am I doing wrong?

type: 'custom:mod-card'
card:
 type: entity-filter
 show_empty: false
 state_color: true
 entities:
   - entity: binary_sensor.larm_ctc
     name: CTC
 state_filter:
   - 'on'
 card:
   type: entity
   style: |
     ha-card {
       background-color: red
     }

Edit: Switched to conditional card