Examine source code of skycranes

{
  "theme": {
    "images": {
      "theme_frame": "mozillaheader.jpg"
    },
    "colors": {
      "frame": "#413e96",
      "tab_background_text": "#111a42"
    }
  },
  "version": "2.0",
  "name": "skycranes",
  "manifest_version": 2,
  "description": "crane structures in the sky"
}