WP: Featured image as background

featured_image_background.php

<?php

// Featured image as background
add_action('wp_head', 'intw_head');
function intw_head() {
	if( is_page() && !is_front_page() ) {
		if( has_post_thumbnail() ) {
			$featimg = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), 'full', false );
			$featimg_url = $featimg[0];
		} else {
			$featimg_url = get_bloginfo('stylesheet_directory') . '/images/bg.jpg';
		}
		echo '<style type="text/css" media="screen">';
		echo '.builder-module-content-background-wrapper { background: url(' . $featimg_url . ') top center no-repeat; }';
		echo '</style>';
	}
}