where wh define css in html code example

Example 1: link css file in html

<link rel="stylesheet" href="styles.css">

Example 2: vh in css

/*
vh	Relative to 1% of the height of the viewport*
*/
<!DOCTYPE html>
<html>
<head>
<style>
h1 {
  font-size: 20vh;
}
</style>
</head>
<body>

<h1>Hello</h1>

<p>Resize the height of the browser window to see how the font-size of h1 changes.</p>
<p>1vh = 1% of viewport height.</p>
<p>The vh unit is not supported in IE8 and earlier.</p>

</body>
</html>

/*
I hope it will help you.
Namaste
Stay Home Stay Safe
*/