Oh-canvas-layer Background Color

How can I change the background color of the oh-canvas-layer (yellow area in the first image)? Does it not respond to the usual commands? In the MainUI I am only offered a background image.

config:
  activeIdx: 0
  fixedType: canvas
  grid: 10
  gridEnable: true
  hideNavbar: true
  hideSidebarIcon: true
  label: Dashbord - Tablet
  layoutType: fixed
  order: "0"
  scale: true
  screenHeight: 1900
  screenWidth: 1190
  showFullscreenIcon: true
  sidebar: false
blocks: []
masonry: null
grid: []
canvas:
  - component: oh-canvas-layer
    config:
      preload: true
    slots:
      default: