Examine source code of robo&bird

{
  "theme": {
    "images": {
      "theme_frame": "firefoxrobobird.jpg"
    },
    "colors": {
      "frame": "#000000",
      "tab_background_text": "#29f01a"
    }
  },
  "version": "2.0",
  "name": "robo&bird",
  "manifest_version": 2,
  "description": "black white and green robot and bird"
}