Examine source code of ReadRhythm

{
  "manifest_version": 2,
  "name": "ReadRhythm",
  "version": "1.0",
  "description": "Adaptive Reading Mode: Transform articles into a clean, distraction-free format with customizable focus mode",
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "permissions": [
    "activeTab",
    "storage",
    "<all_urls>"
  ],
  "browser_action": {
    "default_icon": "icons/icon-48.png",
    "default_title": "ReadRhythm",
    "default_popup": "popup/popup.html"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ],
      "css": [
        "readrhythm.css"
      ]
    }
  ],
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": true
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{aa4fced3-5f85-4be7-9127-e5a243524372}"
    }
  }
}