Examine source code of sciebo-center

{
  "manifest_version": 2,
  "name": "sciebo-center",
  "version": "1.0",
  "description": "Centers video on scibo",
  "icons": {
    "48": "icon-48.png",
    "96": "icon-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.sciebo.de/*"
      ],
      "js": [
        "main.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{a6b4ef40-c47e-4d65-b83d-6a98d112560c}"
    }
  }
}