Examine source code of Dark Mode Toggle

{
  "manifest_version": 2,
  "name": "Dark Mode Toggle",
  "version": "1.0",
  "description": "Toggle dark mode on any website with a simple switch.",
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Dark Mode Toggle"
  },
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "dark-mode.css"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{4f0d7719-a13c-4aff-9bd1-7e749db8283d}"
    }
  }
}