Examine source code of Caster

{
  "theme": {
    "images": {
      "theme_frame": "caster_persona_header.jpg"
    },
    "colors": {
      "frame": "#000000",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Caster",
  "manifest_version": 2,
  "description": "Persona for the Caster video game.\n\n<a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/fc7037f69177dad030cf1c8fbc67bfc256682d23ebf6f8f244ce586f0966cb54/http%3A//www.casterthegame.com\">http://www.casterthegame.com</a>"
}