Examine source code of Custom CSS rules

{
  "manifest_version": 3,
  "name": "Custom CSS Injector",
  "version": "1.1",
  "description": "A Firefox extension to inject custom CSS into any website.",
  "author": "Sina Jalalvandi",
  "homepage_url": "https://sinajalalvandi.ir",
  "permissions": [
    "storage",
    "activeTab",
    "scripting"
  ],
  "host_permissions": [
    "<all_urls>"
  ],
  "background": {
    "scripts": [
      "background/background.js"
    ]
  },
  "action": {
    "default_icon": {
      "48": "icons/icon-48.png",
      "96": "icons/icon-96.png"
    },
    "default_title": "Customer CSS Injector",
    "default_popup": "popup/popup.html"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content_scripts/injector.js"
      ],
      "run_at": "document_idle",
      "all_frames": false
    }
  ],
  "icons": {
    "48": "icons/icon-48.png",
    "96": "icons/icon-96.png"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "fccssi@sinajalalvandi.ir",
      "strict_min_version": "58.0"
    }
  }
}