Examine source code of CAT Calculator

{
  "manifest_version": 3,
  "name": "CAT Calculator",
  "version": "1.0",
  "description": "A replica of the CAT onscreen calculator for practice.",
  "action": {
    "default_popup": "popup.html",
    "default_title": "CAT Calculator",
    "default_icon": "calculator.png"
  },
  "icons": {
    "16": "calculator.png",
    "32": "calculator.png",
    "48": "calculator.png",
    "96": "calculator.png"
  },
  "content_security_policy": {
    "extension_pages": "script-src 'self';"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "cat-calculator@nemalovessaksham.com",
      "strict_min_version": "109.0"
    }
  }
}