Examine source code of RCP Stylo

{
  "name": "RCP Stylo",
  "description": "Design cool pages easily with custom CSS extension",
  "version": "1.9",
  "permissions": [
    "activeTab",
    "storage"
  ],
  "options_page": "options.html",
  "browser_action": {
    "default_icon": "icon.png",
    "default_title": "RCP Stylo",
    "default_popup": "popup.html"
  },
  "manifest_version": 2,
  "browser_specific_settings": {
    "gecko": {
      "id": "{77afd5c3-4ac0-4af2-90c8-7d967d5dbdde}"
    }
  }
}