Examine source code of Hackertosh.css

{
  "manifest_version": 2,
  "name": "Hackertosh.css",
  "version": "1.0",
  "description": "Hackertosh.css - Make HackerNews Look Like MacOS 8.",
  "homepage_url": "https://github.com/anthmn/hackertosh.css",
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "permissions": [
    "tabs",
    "*://news.ycombinator.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://news.ycombinator.com/*"
      ],
      "css": [
        "index.css"
      ]
    }
  ],
  "web_accessible_resources": [
    "assets/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "anthmn@hackertosh.css"
    }
  }
}