Examine source code of Starlight Grotto

{
  "theme": {
    "images": {
      "theme_frame": "StarlightGrotto_hd.jpg"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Starlight Grotto",
  "manifest_version": 2,
  "description": "Firefox Persona version of my “Starlight Grotto” wallpaper. 3D artwork by Ryan Bliss. Persona Designed by Mark Hamilton for Digital Blasphemy. Wallpaper available at <a href=\"https://outgoing.prod.mozaws.net/v1/a37d2a9b48678ecf87acda50053977b196235e78ededc7c371fb885a48d6a47c/http%3A//digitalblasphemy.com/preview.shtml%3Fi=starlightgrotto1\" rel=\"nofollow\">http://digitalblasphemy.com/preview.shtml?i=starlightgrotto1</a>"
}