Examine source code of Google Map Dark Mode

{
  "manifest_version": 3,
  "name": "Google Map Dark Mode",
  "version": "1.0.1",
  "description": "Dark mode for Google Maps on the web: dark map plus recoloured interface. Unofficial; not affiliated with Google.",
  "browser_specific_settings": {
    "gecko": {
      "id": "google-map-dark-mode@charlie754.github.io",
      "strict_min_version": "140.0",
      "data_collection_permissions": {
        "required": [
          "none"
        ]
      }
    },
    "gecko_android": {
      "strict_min_version": "142.0"
    }
  },
  "permissions": [
    "alarms",
    "declarativeNetRequestWithHostAccess",
    "storage"
  ],
  "host_permissions": [
    "https://www.google.com/*",
    "https://www.google.co.uk/*",
    "https://www.google.de/*",
    "https://www.google.fr/*",
    "https://www.google.it/*",
    "https://www.google.es/*",
    "https://www.google.nl/*",
    "https://www.google.pl/*",
    "https://www.google.se/*",
    "https://www.google.com.tr/*",
    "https://www.google.ca/*",
    "https://www.google.com.mx/*",
    "https://www.google.com.br/*",
    "https://www.google.co.jp/*",
    "https://www.google.co.in/*",
    "https://www.google.co.id/*",
    "https://www.google.co.kr/*",
    "https://www.google.com.hk/*",
    "https://www.google.com.tw/*",
    "https://www.google.com.sg/*",
    "https://www.google.com.au/*",
    "https://maps.google.com/*",
    "https://www.gstatic.com/maps/res/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "content_scripts": [
    {
      "matches": [
        "https://www.google.com/maps",
        "https://www.google.com/maps/*",
        "https://www.google.com/maps?*",
        "https://www.google.co.uk/maps",
        "https://www.google.co.uk/maps/*",
        "https://www.google.co.uk/maps?*",
        "https://www.google.de/maps",
        "https://www.google.de/maps/*",
        "https://www.google.de/maps?*",
        "https://www.google.fr/maps",
        "https://www.google.fr/maps/*",
        "https://www.google.fr/maps?*",
        "https://www.google.it/maps",
        "https://www.google.it/maps/*",
        "https://www.google.it/maps?*",
        "https://www.google.es/maps",
        "https://www.google.es/maps/*",
        "https://www.google.es/maps?*",
        "https://www.google.nl/maps",
        "https://www.google.nl/maps/*",
        "https://www.google.nl/maps?*",
        "https://www.google.pl/maps",
        "https://www.google.pl/maps/*",
        "https://www.google.pl/maps?*",
        "https://www.google.se/maps",
        "https://www.google.se/maps/*",
        "https://www.google.se/maps?*",
        "https://www.google.com.tr/maps",
        "https://www.google.com.tr/maps/*",
        "https://www.google.com.tr/maps?*",
        "https://www.google.ca/maps",
        "https://www.google.ca/maps/*",
        "https://www.google.ca/maps?*",
        "https://www.google.com.mx/maps",
        "https://www.google.com.mx/maps/*",
        "https://www.google.com.mx/maps?*",
        "https://www.google.com.br/maps",
        "https://www.google.com.br/maps/*",
        "https://www.google.com.br/maps?*",
        "https://www.google.co.jp/maps",
        "https://www.google.co.jp/maps/*",
        "https://www.google.co.jp/maps?*",
        "https://www.google.co.in/maps",
        "https://www.google.co.in/maps/*",
        "https://www.google.co.in/maps?*",
        "https://www.google.co.id/maps",
        "https://www.google.co.id/maps/*",
        "https://www.google.co.id/maps?*",
        "https://www.google.co.kr/maps",
        "https://www.google.co.kr/maps/*",
        "https://www.google.co.kr/maps?*",
        "https://www.google.com.hk/maps",
        "https://www.google.com.hk/maps/*",
        "https://www.google.com.hk/maps?*",
        "https://www.google.com.tw/maps",
        "https://www.google.com.tw/maps/*",
        "https://www.google.com.tw/maps?*",
        "https://www.google.com.sg/maps",
        "https://www.google.com.sg/maps/*",
        "https://www.google.com.sg/maps?*",
        "https://www.google.com.au/maps",
        "https://www.google.com.au/maps/*",
        "https://www.google.com.au/maps?*",
        "https://maps.google.com/*"
      ],
      "js": [
        "content/theme.js",
        "content/widget.js"
      ],
      "css": [
        "content/theme.css"
      ],
      "run_at": "document_start",
      "all_frames": false
    }
  ],
  "action": {
    "default_popup": "popup/popup.html",
    "default_title": "Google Map Dark Mode",
    "default_icon": {
      "16": "icons/icon-16.png",
      "32": "icons/icon-32.png",
      "48": "icons/icon-48.png",
      "128": "icons/icon-128.png"
    }
  },
  "options_ui": {
    "page": "options/options.html",
    "open_in_tab": true
  },
  "icons": {
    "16": "icons/icon-16.png",
    "32": "icons/icon-32.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "declarative_net_request": {
    "rule_resources": [
      {
        "id": "dark_map",
        "enabled": true,
        "path": "rules/dark-map.json"
      }
    ]
  }
}