Examine source code of Dark Mode Toggle

{
  "manifest_version": 2,
  "name": "Dark Mode Toggle",
  "version": "1.0",
  "description": "Toggle dark mode for any website.",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icons/dark-mode-48.png",
    "default_popup": "popup.html",
    "default_title": "Dark Mode Toggle"
  },
  "icons": {
    "48": "icons/dark-mode-48.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{511dc337-0efd-4439-8aea-3e2fbc306dab}"
    }
  }
}