Examine source code of XCustomizer

{
  "manifest_version": 3,
  "name": "XCustomizer",
  "version": "0.1",
  "description": "Customize x, change favicon, title, logo and more. New features will be added from time to time. Icon by pch.vector on freepik ~ =ω=",
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "action": {
    "default_popup": "settings.html"
  },
  "permissions": [
    "storage"
  ],
  "content_scripts": [
    {
      "js": [
        "scripts/favicon.js",
        "scripts/menu_logo.js",
        "scripts/popup.js",
        "scripts/title.js"
      ],
      "matches": [
        "https://*.twitter.com/*"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "xcustomizer@qatoqat.com"
    }
  }
}