Examine source code of RTT Route Maps

{
  "manifest_version": 3,
  "name": "RTT Maps",
  "version": "0.1.2",
  "description": "Augments Realtime Trains service pages with an interactive route map.",
  "content_scripts": [
    {
      "matches": [
        "https://www.realtimetrains.co.uk/service/gb-nr:*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_idle",
      "world": "MAIN"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "rtt-maps@davwheat.dev",
      "strict_min_version": "128.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}