Examine source code of Archetypal Images

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "rgba(229,230,232,1)",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Archetypal Images",
  "manifest_version": 2,
  "description": "Official theme of <a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/64c6e50b1fc37edfde12e4fd3882c7a125c4304e9c7d464db995faf2b1d16042/http%3A//Archetypalimages.com\">Archetypalimages.com</a>"
}