Lovelace: Landroid card

I am fighting hell to have a transparent color for the Landroid card … using card_mod.
Has someone succeeded to do so ??

Norhing is working for me :

type: 'custom:landroid-card'
style: |
  ha-card {
    --lc-background: #17A8F4;
    --lc-spacing: 5px;
  }

P.S. thanks for the good work !

For information, I am working on building my own dashboard with the entities I need …
… Almost finished :