Examine source code of Paint Me Twilight

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#180829",
      "tab_background_text": "#f5e8ff"
    }
  },
  "version": "2.0",
  "name": "Paint Me Twilight",
  "manifest_version": 2,
  "description": "<a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/9d48e3738c1386f72cdd40f00493e3089a8b95e86bd661f8596bcf630329aa11/http%3A//www.freepik.com\">http://www.freepik.com</a>"
}