Responsive grid layout backgrounds for Bootstrap.

griddle.php

<?php

if ( isset( $_GET['grid'] ) ) {
	add_action( 'wp_print_styles', function () { ?>
		<style type="text/css">

			@media (min-width: 768px) {
				body {
					background: url("http://griddle.it/720px-12-30px") repeat-y center top !important;
				}
			}

			@media (min-width: 992px) {
				body {
					background: url("http://griddle.it/940px-12-30px") repeat-y center top !important;
				}
			}

			@media (min-width: 1200px) {
				body {
					background: url("http://griddle.it/1140px-12-30px") repeat-y center top !important;
				}
			}
		</style>
	<?php } );
}