Examine source code of Minimal Theme for Google

{
  "manifest_version": 2,
  "name": "Minimal Theme for Google",
  "version": "1.0",
  "description": "A clean, distraction-free theme for Google Search, Gmail, Drive, Calendar, and News with optional dark mode and compact density.",
  "permissions": [
    "storage",
    "activeTab"
  ],
  "icons": {
    "128": "icons/logo_128.png"
  },
  "content_scripts": [
    {
      "matches": [
        "*://www.google.com/*",
        "*://mail.google.com/*",
        "*://drive.google.com/*",
        "*://calendar.google.com/*",
        "*://news.google.com/*"
      ],
      "css": [
        "minimal.css"
      ],
      "js": [
        "content.js"
      ],
      "run_at": "document_idle"
    }
  ],
  "browser_action": {
    "default_title": "Minimal Theme for Google",
    "default_icon": "icons/logo_128.png",
    "default_popup": "popup.html"
  },
  "options_ui": {
    "page": "popup.html",
    "open_in_tab": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "{9f2b30b3-de05-40c3-a868-76852ca6045c}"
    }
  }
}