Examine source code of Fast Calc

{
  "manifest_version": 3,
  "name": "Fast Calc",
  "version": "3.0.0",
  "description": "Quickly perform calculations by selecting numbers on webpage.",
  "permissions": [
    "scripting",
    "activeTab"
  ],
  "action": {
    "default_popup": "popup.html",
    "default_title": "Fast Calculator"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "dist/content.bundle.js"
      ]
    }
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "ankit@ankitsweng.tech",
      "strict_min_version": "60.0"
    }
  }
}