Examine source code of Grayscale Websites

{
  "manifest_version": 3,
  "name": "Grayscale Websites",
  "version": "1.0",
  "description": "Turn websites grayscale.",
  "icons": {
    "48": "icon.png"
  },
  "developer": {
    "name": "Jonatham VKZ",
    "url": "https://userfile.org"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "grayscale-websites@userfile.org",
      "strict_min_version": "109.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  },
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "action": {
    "default_icon": "icon.png",
    "default_title": "Grayscale Settings",
    "default_popup": "popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "options_ui": {
    "page": "options.html",
    "browser_style": true
  }
}