Examine source code of Dark Mode Plus

{
  "manifest_version": 2,
  "name": "Dark Mode Plus",
  "version": "1.0",
  "description": "Enable dark mode on any website with a simple toggle. AMO-safe.",
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_title": "Dark Mode Plus",
    "default_popup": "popup.html"
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "karolinamicha.l.s.ki4.33@gmail.com",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}