Examine source code of SteamTrades Dark Mode

{
  "manifest_version": 3,
  "name": "SteamTrades Dark Mode",
  "version": "1.2",
  "description": "Adds a dark mode toggle to SteamTrades website with a popup menu",
  "author": "Bardia",
  "permissions": [
    "storage",
    "activeTab",
    "scripting"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://www.steamtrades.com/*"
      ],
      "css": [
        "styles.css"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "action": {
    "default_popup": "popup.html"
  },
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "steamtrades-dark-mode@bardia.example.com",
      "strict_min_version": "109.0"
    }
  }
}