Examine source code of Ancient Cahokia

{
  "theme": {
    "images": {
      "theme_frame": "firefox-skin-header-cahokia.jpg"
    },
    "colors": {
      "frame": "#872626",
      "tab_background_text": "#00000d"
    }
  },
  "version": "2.0",
  "name": "Ancient Cahokia",
  "manifest_version": 2,
  "description": "Imagery showing the Temple of the Sun (aka \"Monk's Mound\") which was once the center of civilization in much of North America. (This is my very first attempt at creating a Persona!)"
}