Examine source code of RN

{
  "manifest_version": 2,
  "name": "RN",
  "version": "1.0",
  "description": "Change le CSS d'observium",
  "icons": {
    "48": "icons/rn48.png",
    "96": "icons/rn96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://192.168.245.235/*"
      ],
      "js": [
        "changecss.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{1ed39795-413b-4d7c-a5b6-5710a049a7c9}"
    }
  }
}