css - Wordpress how to use post image to dynamically set the url background in css

Question

I'm trying to dynamically add background inside CSS using php, using the Wordpress post image.

background: <?php if(has_post_thumbnail()){ 
                $img = wp_get_attachment_image_src(get_post_thumbnail_id($post->ID), 'destacados');
                echo 'url(".$img['0'].") no-repeat center'  } ?>;

Answer 1

background: <?php if(has_post_thumbnail()){ 
                $img = wp_get_attachment_image_src(get_post_thumbnail_id($post->ID), 'destacados');
                echo "url('".$img['0']."') no-repeat center";
             } ?>;

引号是错误的，并且缺少分号。