Examine source code of Text Spacing Customizer

{
  "manifest_version": 2,
  "name": "Text Spacing Customizer",
  "version": "1.0",
  "description": "Adjust text spacing for better readability.",
  "icons": {
    "48": "icon.png"
  },
  "browser_action": {
    "default_popup": "popup.html",
    "default_icon": "icon.png"
  },
  "permissions": [
    "activeTab"
  ],
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "popup.js"
      ],
      "css": [
        "popup.css"
      ]
    }
  ],
  "browser_specific_settings": {
    "gecko": {
      "id": "{afa11c6a-b320-4e9d-bfa7-4ab720bb7cf7}"
    }
  }
}