Position of 2 vertical stacks

Configuration Frontend
9

i took it from here : 🔹 Card-mod - Add css styles to any lovelace card - #1731 by Ildar_Gabdullin?

title: "Home"
path: "home"
panel: true
cards:
  type: custom:mod-card
  card_mod:
    style:
      hui-horizontal-stack-card $: |
        div#root > :first-child > * {
          width: 30%;
          flex: auto; 
        }
        div#root > :last-child > * {
          width: 70%;
          flex: auto; 
        }
  card:
    - type: horizontal-stack
      cards:

but I get a white screen …