Examine source code of Clouds in blue

{
  "manifest_version": 2,
  "version": "1.0",
  "name": "Blue sky clouds",
  "theme": {
    "images": {
      "additional_backgrounds": [
        "images/0.jpg"
      ]
    },
    "properties": {
      "additional_backgrounds_alignment": [
        "center center"
      ],
      "additional_backgrounds_tiling": [
        "repeat"
      ]
    },
    "colors": {
      "toolbar": "rgb(0, 163, 223)",
      "toolbar_text": "rgb(255, 255, 255)",
      "frame": "rgb(0, 130, 193)",
      "tab_background_text": "rgb(0, 39, 130)",
      "toolbar_field": "rgb(206, 232, 255)",
      "toolbar_field_text": "rgb(0, 0, 0)",
      "tab_line": "rgb(0, 245, 255)",
      "popup": "rgb(214, 224, 255)",
      "popup_text": "rgb(0, 96, 255)",
      "tab_loading": "rgb(0, 245, 255)"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{111dd3d6-e92e-49f8-ad6f-b4debd5a4291}"
    }
  }
}