Examine source code of Instantly toggle dark

{
  "manifest_version": 2,
  "name": "Dark Mode Toggle",
  "version": "1.0",
  "description": "Toggle dark mode on any website.",
  "browser_action": {
    "default_icon": {
      "48": "icon.png"
    },
    "default_title": "Toggle Dark Mode"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "permissions": [
    "tabs",
    "<all_urls>"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{0ba936c7-60d9-4e3a-abb4-d562304a1307}"
    }
  }
}