Examine source code of CSS Viewer CJ

{
  "manifest_version": 2,
  "name": "CSS Viewer",
  "version": "1.0",
  "description": "View the CSS properties of any element on a webpage by hovering over it.",
  "icons": {
    "48": "icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "browser_action": {
    "default_icon": "icon.png",
    "default_popup": "popup.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{ee7bf8cb-1661-4448-a1f9-e2b024a78a3e}"
    }
  }
}