Examine source code of betertube

{
  "name": "Cleantube",
  "description": "Use it as you like it, a better css for youtube",
  "version": "1.0",
  "manifest_version": 2,
  "content_scripts": [
    {
      "matches": [
        "https://*.youtube.com/*"
      ],
      "css": [
        "overflow.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{3a5e08a8-8303-443a-b973-c0fe5deddba9}"
    }
  }
}