Examine source code of Dark Mode - for selective sites

{
  "manifest_version": 2,
  "name": "Universal Dark Mode",
  "version": "1.1",
  "description": "Adds dark mode to any website with selective site control - whitelist, blacklist, or all sites",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "dark-mode.css"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Toggle Dark Mode",
    "default_icon": {
      "32": "icons/icon-32.ico"
    }
  },
  "icons": {
    "32": "icons/icon-32.ico"
  },
  "web_accessible_resources": [
    "dark-mode.css"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{38319938-3b1d-4043-8463-94508ccf316b}"
    }
  }
}