Examine source code of Reading Level Detector

{
  "manifest_version": 2,
  "name": "Reading Level Detector",
  "version": "1.3",
  "description": "Detect and analyze the reading level of any webpage content with detailed metrics.",
  "permissions": [
    "activeTab",
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_title": "Reading Level Detector"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d6b8f1a5-d574-4f4d-8e79-11445ba3fd17}"
    }
  }
}