<!DOCTYPE html>
<html>
<head>
<style>
body {
background-image: url('img_tree.png');
background-repeat: no-repeat;
}
</style>
</head>
<body>
<button type="button" onclick="myFunction()">Position background image</button>
<script>
function myFunction() {
document.body.style.backgroundPosition="top right";
}
</script>
</body>
</html>