Examine source code of Font Changor

{
  "manifest_version": 3,
  "name": "Font Changer",
  "version": "1.0",
  "description": "Customize website fonts.",
  "action": {
    "default_popup": "popup.html",
    "default_icon": "font_changer.png"
  },
  "icons": {
    "128": "font_changer.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "dascalosh7052003csvvj@hotmail.com"
    }
  }
}