Examine source code of YNAB Percentage view

{
  "manifest_version": 2,
  "name": "YNAB Percentage view",
  "version": "1.2",
  "content_scripts": [
    {
      "matches": [
        "https://app.youneedabudget.com/*/budget*"
      ],
      "js": [
        "index.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "ynab_percentage_webextension@sylvain.dev",
      "strict_min_version": "52.0"
    }
  },
  "icons": {
    "32": "icons/icon-32x32.png",
    "72": "icons/icon-72x72.png",
    "96": "icons/icon-96x96.png",
    "128": "icons/icon-128x128.png",
    "144": "icons/icon-144x144.png",
    "152": "icons/icon-152x152.png",
    "192": "icons/icon-192x192.png"
  }
}