Examine source code of Firefox 3.0

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#000"
    }
  },
  "version": "2.0",
  "name": "Firefox 3.0",
  "manifest_version": 2,
  "description": "Designed by Kyle Dickerson\n\nA simple theme for all versions of Firefox. Features a transparent background so you can use this with any color background and the theme will not clash.\n\nFeel free to use this wherever with whatever you please. Just be sure to give credit. Thanks!"
}