Examine source code of Dark Gradient Pattern

{
  "theme": {
    "images": {
      "theme_frame": "header.png"
    },
    "colors": {
      "frame": "#1a1a1a",
      "tab_background_text": "#ffffff"
    }
  },
  "version": "2.0",
  "name": "Dark Gradient Pattern",
  "manifest_version": 2,
  "description": "Tacky rework of Bloody Red theme so I can use it in FF 39.0\n\nBased on Bloody Red by Jivko Evgeniev:\n<a rel=\"nofollow\" href=\"https://addons.mozilla.org/en-us/firefox/addon/a-bloody-red-theme/\">https://addons.mozilla.org/en-us/firefox/addon/a-bloody-red-theme/</a>\n<a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/d2c8541ccfb237f5ddb7e11130799444994578e69d41d1a9e16539951c638518/http%3A//web-goodies.net/firefox/\">http://web-goodies.net/firefox/</a>\n<a rel=\"nofollow\" href=\"https://outgoing.prod.mozaws.net/v1/e68ca29b006a17ac1753146cbc2d595786fa3ee215f6f927339c513d1e27e871/http%3A//web-goodies.net/\">http://web-goodies.net/</a>"
}