Examine source code of YouTube Grid Pro

{
  "manifest_version": 2,
  "name": "YouTube Grid Pro",
  "version": "2.0.1",
  "description": "Customize YouTube home grid density, Shorts visibility, and screen width behavior from the toolbar.",
  "permissions": [
    "storage",
    "tabs"
  ],
  "browser_action": {
    "default_title": "YouTube Grid Pro",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "96": "icons/icon-96.png"
    }
  },
  "options_ui": {
    "page": "popup.html",
    "browser_style": true,
    "open_in_tab": true
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*",
        "*://youtube.com/*",
        "*://m.youtube.com/*"
      ],
      "css": [
        "youtube-grid.css"
      ],
      "js": [
        "youtube-grid.js"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "youtube-grid-pro@local",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    }
  }
}