Examine source code of Witcher 4

{
  "manifest_version": 2,
  "version": "2.0",
  "name": "Witcher 4",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center top"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(38, 38, 38)",
      "toolbar_text": "rgb(252, 0, 0)",
      "frame": "rgb(0, 0, 0)",
      "tab_background_text": "rgb(255, 255, 255)",
      "toolbar_field": "rgb(7, 7, 7)",
      "toolbar_field_text": "rgb(252, 0, 0)",
      "tab_line": "rgb(252, 0, 0)",
      "popup": "rgb(44, 41, 41)",
      "popup_text": "rgb(252, 0, 0)",
      "icons": "rgb(252, 0, 0)",
      "tab_loading": "rgb(252, 0, 0)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9f0cf659-bff2-46fc-9ed1-4faadd8b1881}"
    }
  }
}