Examine source code of Windows Wallpaper Dark

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Windows Wallpaper Dark",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.png"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(72, 67, 217)",
      "toolbar_text": "rgb(59, 54, 188)",
      "frame": "rgb(102, 98, 217)",
      "tab_background_text": "rgb(85, 80, 242)",
      "toolbar_field": "rgb(81, 84, 140)",
      "toolbar_field_text": "rgb(59, 54, 188)",
      "tab_line": "rgb(5, 24, 52)",
      "popup": "rgb(5, 16, 38)",
      "popup_text": "rgb(32, 22, 109)",
      "tab_loading": "rgb(5, 24, 52)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{277dbdd2-e0d8-4fa1-8ddb-fe563dfc6bc3}"
    }
  }
}