Examine source code of Privacy Veil

{
  "manifest_version": 3,
  "name": "PrivacyVeil",
  "version": "1.0.0",
  "description": "Privacy-first dark mode for Firefox/LibreWolf",
  "browser_specific_settings": {
    "gecko": {
      "id": "pookielinuxuser@tutamail.com"
    }
  },
  "permissions": [
    "storage",
    "activeTab"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "service_worker": "background.js",
    "scripts": [
      "background.js"
    ]
  },
  "action": {
    "default_popup": "popup.html",
    "default_icons": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "dark-mode.css"
      ],
      "run_at": "document_start",
      "all_frames": true
    }
  ]
}