Examine source code of Custom X Fonts

{
  "manifest_version": 2,
  "name": "X Font Customizer",
  "description": "Change the font and font size on X.com (Twitter)",
  "version": "1.0",
  "permissions": [
    "storage",
    "tabs",
    "https://x.com/*",
    "https://twitter.com/*",
    "https://fonts.googleapis.com/*",
    "https://fonts.gstatic.com/*"
  ],
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icon16.png",
      "48": "icon48.png",
      "128": "icon128.png"
    }
  },
  "icons": {
    "16": "icon16.png",
    "48": "icon48.png",
    "128": "icon128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "https://x.com/*",
        "https://twitter.com/*"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "x-font-customizer@jsellurs.com",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ],
        "optional": []
      }
    }
  }
}