Examine source code of Wide Twitter

{
  "manifest_version": 2,
  "name": "Wide Twitter",
  "version": "1.0",
  "description": "the world needs it",
  "icons": {
    "48": "icons/wide-48.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.twitter.com/*"
      ],
      "css": [
        "css/block.css",
        "css/widen.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{912af789-fe7a-4346-a8c3-b1b9326cad50}"
    }
  }
}