Examine source code of Jackassworld - Gray

{
  "theme": {
    "images": {
      "theme_frame": "firefox_jawheader.png"
    },
    "colors": {
      "frame": "#ffffff",
      "tab_background_text": "#c0c0c0"
    }
  },
  "version": "2.0",
  "name": "Jackassworld - Gray",
  "manifest_version": 2,
  "description": "For all Jackass fans. Light gray/black/dark gray."
}