Examine source code of Pure Win

{
  "theme": {
    "images": {
      "theme_frame": "purewin_head.png"
    },
    "colors": {
      "frame": "#a8a8a8",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Pure Win",
  "manifest_version": 2,
  "description": "Firefox is pure win, so why not show it?  Stylized letters on a backdrop of black.  Firefox logo with a fractal behind it adds a touch of awesomeness, as well."
}