Examine source code of Scryfall - Casual Challenge Checker

{
  "name": "Scryfall - Casual Challenge Checker",
  "description": "Scryfall.com deck checker for 'Casual Challenge', a custom Magic the Gathering format created by XieLong and Janosch.exe.",
  "version": "1.0.0",
  "manifest_version": 3,
  "author": "Raoul Zander",
  "homepage_url": "https://www.casualchallenge.gg/",
  "icons": {
    "16": "/icons/16x.png",
    "32": "/icons/32x.png",
    "48": "/icons/48x.png",
    "128": "/icons/128x.png"
  },
  "action": {
    "default_title": "Scryfall - Casual Challenge Checker",
    "default_popup": "popup.html",
    "default_icon": {
      "16": "/icons/16x.png",
      "32": "/icons/32x.png",
      "48": "/icons/48x.png",
      "128": "/icons/128x.png"
    }
  },
  "permissions": [
    "storage",
    "scripting"
  ],
  "host_permissions": [
    "https://*.scryfall.com/*"
  ],
  "externally_connectable": {
    "matches": [
      "https://*.scryfall.com/*"
    ]
  },
  "background": {
    "scripts": [
      "service-worker.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://scryfall.com/*/decks/*",
        "https://scryfall.com/search?*",
        "https://scryfall.com/card/*",
        "https://scryfall.com/sets/*"
      ],
      "css": [
        "styles/content-script.css"
      ],
      "js": [
        "content-script.js"
      ],
      "run_at": "document_start"
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "addon@casual-challenge.org",
      "strict_min_version": "109.0"
    }
  }
}