<!DOCTYPE html>
<html>
<head>
<title>Title of the document</title>
<style>
body {
margin: 0;
}
img {
position: fixed;
width: 0;
height: 0;
padding: 40vh 40vw;
background: url(https://images.unsplash.com/photo-1491796014055-e6835cdcd4c6?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=500&q=60) no-repeat;
background-size: cover;
}
</style>
</head>
<body>
<img src="http://placehold.it/1500x1000" alt="Background-size example" />
</body>
</html>