Examine source code of Github XP

{
  "name": "Github XP",
  "version": "5.0.4resigned1",
  "description": "Github <3 Microsoft!",
  "manifest_version": 2,
  "content_scripts": [
    {
      "matches": [
        "https://github.com/*"
      ],
      "css": [
        "xp.css"
      ]
    }
  ],
  "icons": {
    "16": "icon-16.png",
    "48": "icon-48.png",
    "128": "icon-128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{78b1a251-b32f-4fd2-9a5d-df6a13e0bd0f}"
    }
  }
}