Examine source code of eCarsTrade Dark Mode

{
  "manifest_version": 3,
  "name": "eCarsTrade Dark Mode",
  "version": "1.3.1",
  "description": "Adds a dark mode theme to the eCarsTrade website and includes a calculator with VAT functionality.",
  "browser_specific_settings": {
    "gecko": {
      "id": "{5bed254a-3e78-49ff-9558-e83fa15fcea0}",
      "strict_min_version": "109.0"
    }
  },
  "icons": {
    "48": "icons/icon48.png",
    "96": "icons/icon96.png"
  },
  "permissions": [
    "storage",
    "activeTab"
  ],
  "host_permissions": [
    "https://ecarstrade.com/*",
    "https://*.ecarstrade.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "*://ecarstrade.com/*",
        "*://*.ecarstrade.com/*"
      ],
      "css": [
        "preload.css"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_start"
    }
  ],
  "action": {
    "default_popup": "popup.html",
    "default_title": "Toggle Dark Mode",
    "default_icon": {
      "48": "icons/icon48.png",
      "96": "icons/icon96.png"
    }
  },
  "web_accessible_resources": [
    {
      "resources": [
        "dark-mode.css"
      ],
      "matches": [
        "*://ecarstrade.com/*",
        "*://*.ecarstrade.com/*"
      ]
    }
  ]
}