Examine source code of Connections Helper

{
  "name": "Connections Helper",
  "description": "An extension to mark categories in NYT Connections tiles.",
  "version": "1.0.1",
  "manifest_version": 3,
  "browser_specific_settings": {
    "gecko": {
      "id": "connectionshelperforfirefox@gmail.com",
      "strict_min_version": "109.0"
    }
  },
  "permissions": [
    "activeTab",
    "scripting"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_icon": {
      "128": "/images/icon-128.png"
    }
  },
  "icons": {
    "128": "/images/icon-128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.nytimes.com/games/connections*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "style.css"
      ]
    }
  ]
}