Examine source code of pillirobot

{
  "theme": {
    "images": {
      "theme_frame": "ust.png"
    },
    "colors": {
      "frame": "#999999",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "pillirobot",
  "manifest_version": 2,
  "description": "<a href=\"https://outgoing.prod.mozaws.net/v1/756fb00d9173d7abfe56cf6d9a09907db02627544d234c03eafb32bbe8a0e30c/http%3A//pillirobot.com\" rel=\"nofollow\">pillirobot.com</a> firefox theme"
}