Examine source code of DarkTube

{
  "manifest_version": 2,
  "name": "DarkTube",
  "version": "0.7.0",
  "description": "Forces YouTube to use dark theme.",
  "author": "Ezerous",
  "homepage_url": "https://github.com/Ezerous/DarkTube",
  "browser_specific_settings": {
    "gecko": {
      "id": "{2b686e8e-e569-4940-9b64-55cfe0bb2599}"
    }
  },
  "icons": {
    "48": "icons/darktube_logo.svg",
    "96": "icons/darktube_logo.svg"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.youtube.com/*"
      ],
      "css": [
        "css/darktube.css"
      ]
    }
  ],
  "permissions": [
    "cookies",
    "*://*.youtube.com/"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  }
}