Allow a custom background on Posts in the Kickstart Pro theme (http://docs.leanthemes.co/article/31-kickstart-customise-custom-background-posts)

single.php

<?php
/**
 * Kickstart Pro
 *
 * @author  Lean Themes
 * @license GPL-2.0+
 * @link    http://demo.leanthemes.co/kickstart/
 */

add_action( 'genesis_after_header', 'kickstart_page_before' );
// Add before content section
function kickstart_page_before() {
	// If a Featured Image is set for this page, create the background div
	if ( has_post_thumbnail() ) {
		echo '<div class="before-content"></div>';
	}
}

genesis();