Examine source code of Css Layout Hack

{
  "version": "2.2.2",
  "manifest_version": 2,
  "name": "Css Layout Hack",
  "author": "reza rastegar",
  "description": "You can see website layers with different colors easily",
  "icons": {
    "16": "assets/img/logo.png",
    "32": "assets/img/logo.png",
    "48": "assets/img/logo.png",
    "128": "assets/img/logo.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ],
    "persistent": false
  },
  "permissions": [
    "activeTab",
    "storage"
  ],
  "browser_action": {
    "default_title": "Css Layout Hack",
    "default_popup": "popup.html"
  },
  "web_accessible_resources": [
    "assets/img/logo.png"
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{d059fad3-9cdc-496c-a44b-02a90d89acde}"
    }
  }
}