examples/scalable-pictures.html

<!DOCTYPE html>
<html lang="en">
<head>

	<meta charset="utf-8">
	<title>Scalable Pictures</title>

	<style>
		picture { width: 50%; }
	</style>

</head>

<body>

	<picture data-scalable src="http://placehold.it/96&text=thumb" data-width="96" data-height="96">
		<source src="http://placehold.it/320&text=320" data-width="320" data-height="320" />
		<source src="http://placehold.it/640&text=640" data-width="640" data-height="640" />
		<img src="http://placehold.it/320&text=fallback" alt="fallback" />
	</picture>

	<script src="../scalable-pictures.js"></script>

</body>
</html>