Examine source code of Readable Marxists

{
  "name": "Readable Marxists",
  "version": "0.4",
  "short_name": "Make marxists.org a little nicer",
  "manifest_version": 2,
  "icons": {
    "16": "./img/16.png",
    "48": "./img/48.png",
    "128": "./img/128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "http://www.marxists.org/*",
        "https://www.marxists.org/*"
      ],
      "css": [
        "readable_marxists.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{e57e8e4b-ef64-449c-91e5-98dfe3921f50}"
    }
  }
}