Examine source code of Back to School

{
  "theme": {
    "images": {
      "theme_frame": "Back-to-School.png"
    },
    "colors": {
      "frame": "#cacaca",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Back to School",
  "manifest_version": 2,
  "description": "Download a matching wallpaper at <a href=\"https://outgoing.prod.mozaws.net/v1/1e6aa9ca366ff7020da9c74f6003d534624a3aaa0b1324fdcf55d27fd007847a/http%3A//wagooh.net/freebies/back-to-school\" rel=\"nofollow\">http://wagooh.net/freebies/back-to-school</a>"
}