Examine source code of Ubuntu Blend

{
  "theme": {
    "images": {
      "theme_frame": "personatop.jpg"
    },
    "colors": {
      "frame": "#ababab",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Ubuntu Blend",
  "manifest_version": 2,
  "description": "Make Firefox on Ubuntu blend in again!  After updating to 10.10, my Firefox got a weird white theme on it, and I personally think it looks horrible.  Make yours look good again with this cool gradient.\nNote that due to size limitations I can't give you a PNG for the header."
}