<!DOCTYPE html>
<html lang="en-US">
<head>
<style>
body{
height: 260px;
background-image: url("ocean.jpg");
background-repeat: no-repeat;
background-size: contain;
color: #ffffff;
}
</style>
</head>
<body>
<h1>CSS background-size Property</h1>
<button onclick="myFunction()">Click Me</button>
<script>
var x = document.getElementsByTagName("body")[0];
function myFunction(){
x.style.backgroundSize = "cover";
}
</script>
<p><strong>Note</strong>: Click on the button to set the background-size to cover.</p> </body>
</html>