Examine source code of lesen

{
  "manifest_version": 2,
  "name": "lesen",
  "version": "1.1resigned1",
  "description": "Changes pages to dark mode and adds hyphens",
  "icons": {
    "48": "icons/ebook-icon.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://*/*"
      ],
      "js": [
        "reading.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{cd9a122e-b622-4d02-b8d5-cf8b75912004}"
    }
  }
}