Examine source code of YouTube Speed Overlay

{
  "manifest_version": 3,
  "name": "YouTube Speed Overlay",
  "version": "1.7",
  "description": "Glass-style overlay for YouTube with instant speed controls up to 16x.",
  "permissions": [
    "storage"
  ],
  "host_permissions": [
    "*://www.youtube.com/*",
    "*://m.youtube.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://www.youtube.com/*",
        "*://m.youtube.com/*"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "content.css"
      ],
      "run_at": "document_end"
    }
  ],
  "action": {
    "default_popup": "popup.html",
    "default_title": "YouTube Speed Overlay Settings"
  },
  "icons": {
    "16": "icons/icon16.png",
    "32": "icons/icon32.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{1e050be6-c1ec-4fb8-be14-197a916c4ff5}",
      "strict_min_version": "109.0"
    }
  }
}