Examine source code of Dark Mode Toggle

{
  "manifest_version": 2,
  "name": "Dark Mode Toggle",
  "version": "1.0",
  "description": "Toggle dark mode for the current web page.",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{5996d221-1577-44ee-8b58-18b194e437ab}"
    }
  }
}