Examine source code of soul gems 1

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#fcfcfc",
      "tab_background_text": "#f1838a"
    }
  },
  "version": "2.0",
  "name": "soul gems 1",
  "manifest_version": 2,
  "description": "Soul gems from Puella Magi Madoka Magica. Credit goes to Jose Pascua of <a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/f7581e883f1c9f7cfc67c3123746956abbca4f55491a68483e7d3ba49dc97547/http%3A//atop-the-hill.tumblr.com\">atop-the-hill.tumblr.com</a>. If you want to use this theme for anything other than Firefox, ask him! :)"
}