:root Selector

root ( ) version added: 1.9

Description: Selects the element that is the root of the document.

In HTML, the root of the document, and thus the element that $(":root") selects, is always the <html> element.

Examples:

Example: Display the tag name of the root element. 

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>css demo</title>

  <style>

  span.fot {
    color: red;
    font-size: 120%;
    font-style: italic;
  }

  </style>

  <script src="//code.jquery.com/jquery-1.10.2.js"></script>
</head>
<body>
  

<div id="log">The root of this document is: </div>

<script>

$( "<b></b>" ).html( $( ":root" )[ 0 ].nodeName ).appendTo( "#log" );

</script>

  
</body>
</html>

Demo: