Examine source code of Per-Site CSS Injector

{
  "manifest_version": 2,
  "name": "Per-Site CSS Injector",
  "version": "1.0",
  "description": "Injects custom CSS to specific websites.",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup/popup.html",
    "default_title": "Custom CSS"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "content-script.js"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{0fad0d10-c470-4820-9cad-a67564205b07}"
    }
  }
}