Examine source code of pro grey

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#E9E9E9",
      "tab_background_text": "#000000"
    }
  },
  "version": "2.0",
  "name": "pro grey",
  "manifest_version": 2,
  "description": "This is a solid color theme based on Lionel Loeb's \"pro grey\" theme on Chromium. I switched to Firefox a few days ago and instantly missed his theme, so I made this version for Firefox. All credit goes to him.\n\nHis site: <a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/19dd9c46471a68ef7baedf99fca966a01fa0e279675ceb55043cf83d99718cbc/http%3A//pix-l.com\">http://pix-l.com</a>"
}