Examine source code of Visual CSS Editor ERT

{
  "manifest_version": 2,
  "name": "Visual CSS Editor",
  "description": "Customize any website visually.",
  "version": "7.6.6",
  "browser_action": {},
  "icons": {
    "16": "icons/icon_16.png",
    "32": "icons/icon_32.png",
    "48": "icons/icon_48.png",
    "64": "icons/icon_64.png",
    "128": "icons/icon_128.png"
  },
  "permissions": [
    "activeTab",
    "scripting",
    "cookies",
    "storage"
  ],
  "host_permissions": [
    "https://visualcsseditor.com/*"
  ],
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "web_accessible_resources": [
    "editor/*"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{23488e97-d44d-40f4-a907-d96d7779dceb}"
    }
  }
}