Every page has <ui-root> inside of <body> as its root.
<!doctype html>
<html>
<head>
<title>vllayout example</title>
<!-- make the layout adapt on mobile devices -->
<meta name="viewport" content="width=device-width, initial-scale=1">
<!-- include your compiled style sheet -->
<link rel="stylesheet" href="/styles.css">
</head>
<body>
<ui-root></ui-root>
</body>
</html>