Examine source code of Furless Booking

{
  "manifest_version": 3,
  "name": "Furless Booking",
  "version": "1.0.0",
  "description": "Flags pet-friendly listings on Booking.com in bold red, even when Booking's own summary box fails to show it.",
  "browser_specific_settings": {
    "gecko": {
      "id": "furless@gdr.name",
      "strict_min_version": "142.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png",
    "128": "icons/icon-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*.booking.com/hotel/*"
      ],
      "js": [
        "src/detect.js",
        "src/content.js"
      ],
      "css": [
        "src/content.css"
      ],
      "run_at": "document_idle"
    }
  ]
}