<!DOCTYPE html>
<html>
<head>
<script src="/lib/jquery-1.12.2.min.js"></script>
<script>
$(document).ready(function(){
$(window).resize(function() {
if ($(this).width() < 728) {
$("body").css("background-color", "yellow");
} else {
$("body").css("background-color", "pink");
}
});
});
</script>
</head>
<body>
<p>Resize the window to change background-color (make the screen's width smaller and larger).</p>
</body>
</html>