Sets the thumbnail image as background to a div

thumb_background.php

<header class="entry-header row" <?php

  if ( $thumbnail_id = get_post_thumbnail_id() ) {
    if ( $image_src = wp_get_attachment_image_src( $thumbnail_id, 'x-large-size' ) )
      printf( ' style="background-image: url(%s);"', $image_src[0] );     
  }

?>>

thumb_background_alternate.php

<?php $image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'large' ); 
	$image = $image[0];	?>
	<div id="primary" class="content-area fader" style="background-image: url('<?php echo $image; ?>');">
		<div id="content" class="site-content" role="main">
			<?php get_template_part( 'content', 'home' ); ?>
		</div><!-- #content -->
	</div><!-- #primary -->