Examine source code of Turning Red Background

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Turning Red Background",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg",
        "images/1.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "left top",
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat",
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(222, 197, 230)",
      "toolbar_text": "rgb(0, 0, 0)",
      "frame": "rgb(208, 191, 230)",
      "tab_background_text": "rgb(0, 0, 0)",
      "toolbar_field": "rgba(255, 255, 255, 0)",
      "toolbar_field_text": "rgb(0, 0, 0)",
      "tab_line": "rgb(207, 186, 230)",
      "popup": "rgb(222, 197, 230)",
      "popup_text": "rgb(0, 0, 0)",
      "tab_loading": "rgb(207, 186, 230)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{b0eeba1b-beaa-4bd9-a3c0-9a6a75ac8a3d}"
    }
  }
}