Examine source code of FocusFlow Startpage

{
  "manifest_version": 3,
  "name": "Custom StartPage",
  "version": "1.0",
  "description": "Overrides the browser's new tab page with your own customizable start page. Edit startpage.html to set your content. Does not open at browser launch or load local files.",
  "icons": {
    "48": "icons/icon48.png"
  },
  "chrome_url_overrides": {
    "newtab": "startpage.html"
  },
  "options_ui": {
    "page": "options.html",
    "open_in_tab": false
  },
  "browser_specific_settings": {
    "gecko": {
      "id": "custom-startpage@thankyoucode"
    }
  }
}