Examine source code of Simple CSS Inserter

{
  "manifest_version": 3,
  "name": "Simple CSS Inserter",
  "version": "3.1",
  "author": "JM",
  "description": "Bring CSS in and out.",
  "icons": {
    "48": "css48.svg",
    "96": "css48.svg"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{5fef998a-5799-43b8-9e34-367b26c46b77}",
      "strict_min_version": "128.0"
    },
    "gecko_android": {
      "strict_min_version": "128.0"
    }
  },
  "host_permissions": [
    "file:///*",
    "http://*/*",
    "https://*/*"
  ],
  "permissions": [
    "menus",
    "scripting",
    "storage"
  ],
  "action": {
    "default_icon": "out16.svg"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "options_ui": {
    "open_in_tab": true,
    "page": "options.html"
  }
}