Examine source code of Custom Style Manager

{
  "manifest_version": 2,
  "name": "Custom Style Manager",
  "author": "Halil Can",
  "version": "1.0.3",
  "description": "Custom Style Manager allows domain-level custom CSS styling for any website you visit.",
  "homepage_url": "https://github.com/HalilCan/customStyleManager",
  "icons": {
    "48": "icons/paintbrush-icon-48.png",
    "96": "icons/paintbrush-icon-96.png"
  },
  "content_scripts": [
    {
      "matches": [
        "<all_urls>"
      ],
      "js": [
        "customStyleApplier.js"
      ]
    }
  ],
  "permissions": [
    "activeTab",
    "tabs",
    "storage"
  ],
  "browser_action": {
    "default_icon": "icons/paintbrush-icon-32.png",
    "default_title": "Custom Style Manager",
    "default_popup": "popup/style_editor.html"
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "talimilat@outlook.com"
    }
  }
}