Examine source code of Custom Tab UI

{
  "manifest_version": 2,
  "name": "Custom Tab UI",
  "version": "1.0",
  "description": "Customize the appearance of tabs in Firefox. Allows users to change the background color and font size of tabs.",
  "permissions": [
    "tabs",
    "activeTab"
  ],
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "128": "icons/icon128.png"
  },
  "background": {
    "scripts": [
      "background.js"
    ]
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": {
      "16": "icons/icon16.png",
      "48": "icons/icon48.png",
      "128": "icons/icon128.png"
    }
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{351ffb08-4a37-497a-8492-14c2a3c00e96}"
    }
  }
}