Examine source code of World-Racers.com

{
  "theme": {
    "images": {
      "theme_frame": "WR_Header_Persona.JPG"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#88d40c"
    }
  },
  "version": "2.0",
  "name": "World-Racers.com",
  "manifest_version": 2,
  "description": "To be used by members of the <a href=\"https://outgoing.prod.mozaws.net/v1/1eec5b252e95ed90eb08c6ca41282bd04353135304ec2597a77bfb4d539847d1/http%3A//www.world-racers.com\" rel=\"nofollow\">www.world-racers.com</a> racing game community, if they so wish to."
}