Examine source code of FourceLabs

{
  "theme": {
    "images": {
      "theme_frame": "FourceLabsFFoxPersonaHeader.jpg"
    },
    "colors": {
      "frame": "#ba1020",
      "tab_background_text": "#0f0a16"
    }
  },
  "version": "2.0",
  "name": "FourceLabs",
  "manifest_version": 2,
  "description": "<a href=\"https://outgoing.prod.mozaws.net/v1/8fa3a38685be803b1689bfa32b1ba9a28d79ceca1a7f56e9c742429574fa8be2/http%3A//www.fourcelabs.com\" rel=\"nofollow\">www.fourcelabs.com</a>"
}