Examine source code of xkdata

{
  "theme": {
    "images": {
      "theme_frame": "xk_top2.png"
    },
    "colors": {
      "frame": "#f2f2f2",
      "tab_background_text": "#dbdbdb"
    }
  },
  "version": "2.0",
  "name": "xkdata",
  "manifest_version": 2,
  "description": "Jaguar XK120 from <a href=\"https://outgoing.prod.mozaws.net/v1/0f1aebfd5613d657d98e23cfe7af1176466fced3da27fb89005a25b2cef9c178/http%3A//xkdata.com\" rel=\"nofollow\">xkdata.com</a>"
}