Examine source code of hipsterify

{
  "manifest_version": 2,
  "name": "Hipster",
  "description": "Change all the pages to sepia",
  "version": "1.2resigned1",
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "css": [
        "css/hipster.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{bc1fcef7-08df-4391-b116-56169b837709}"
    }
  }
}