featured_image_bg.php

<?php
  $image_data = wp_get_attachment_image_src( get_post_thumbnail_id($post->ID), "large" );
?>

<div class="page-header-wrapper" 
     <?php  if(!empty($image_data)) : 
            echo 'style="background-image: url(' . $image_data[0] . '); height:' . $image_data[2] .'px;"'; endif; ?> >
</div>