Examine source code of Dark Mode Switcher lets

{
  "manifest_version": 2,
  "name": "Dark Mode Switcher",
  "version": "1.0",
  "description": "Toggle dark mode on any website with a single click.",
  "permissions": [
    "activeTab",
    "tabs"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "browser_action": {
    "default_title": "Toggle Dark Mode"
  },
  "web_accessible_resources": [
    "darkmode.css"
  ],
  "icons": {
    "48": "icon.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{53c489aa-1a18-4edd-a13e-e20a3f27df2e}"
    }
  }
}