Examine source code of Dark Mode v2

{
  "manifest_version": 2,
  "name": "Dark Mode",
  "version": "1.0",
  "description": "Enable dark mode for web pages",
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_title": "Dark Mode"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{01d968a6-24b8-42a6-abcf-f2b0db5c8e51}"
    }
  }
}