MainUI: Screensaver Design

Add-ons UIs
1

Dear all,
i think i do have a simple issue but i am not able to find help searching in the forum.
Therefore i want to ask:
How to adapt the style parameters of a fixed grid page?
background color and text color

I want the background black and the text white.
This is my current code. But the color is not black and the text is not white

config:
  layoutType: fixed
  fixedType: grid
  screenWidth: 1200
  screenHeight: 1920
  hideNavbar: true
  hideSidebarIcon: true
  label: screensaver_test
  style:
    background: black
  sidebar: true
blocks: []
masonry: null
grid:
  - component: oh-grid-item
    config:
      x: 4
      y: 3
      h: 4
      w: 8
    slots:
      default:
        - component: oh-clock-card
          config:
            timeFontWeight: bold
            noBorder: true
            noShadow: true
            background: grey
            style:
              color: white
canvas: []
2

The background color is set this way.

  --f7-page-bg-color: "#050544"
3

Thank you! This worked. Can you also tell me how to change the color of the text (clock)?