Adding the_post_thumbnail(); via css - php

Question

I'm trying to set my posts page so that each post item loads with it's featured image as it's background. My code is working properly, but how do I add the post thumbnail as the background for each post? My code is attached below
<?php
/**
* The main template file.
*
* This is the most generic template file in a WordPress theme
* and one of the two required files for a theme (the other being style.css).
* It is used to display a page when nothing more specific matches a query.
* E.g., it puts together the home page when no home.php file exists.
* Learn more: http://codex.wordpress.org/Template_Hierarchy
*
* #package Clean Blog
*/
get_header(); ?>
<?php
// Custom loop that adds a clearing class to the first item in each row
$args = array('numberposts' => -1, 'order' => 'ASC' ); //For this example I am setting the arguments to return all posts in reverse chronological order. Odds are this will be a different query for your project
$allposts = get_posts($args);
$numCol = 2; // Set number of columns
// Start Counter
$counter = 0;
foreach ($allposts as $post) {
$content = '<div class="col-md-6 columns-'.$numCol.($counter % $numCol == 0 ? ' first' : '').'">'; // Add class to first column
$content .= '<h3>'.$post->post_title.'</h3>';
$content .= $post->post_content;
$content .= '</div>';
echo $content;
$counter ++;
}
?>
<style type="text/css">
/* Added styles here for the demo, but ideally you would put this in a stylesheet.*/
.columns-2 {
float:left;
}
.first {
clear:both;
margin-left:0;
}
</style>
<!-- /.col-lg-8.col-lg-offset-2.col-md-10.col-md-offset-1 -->
<?php get_footer(); ?>
UPDATE
I've now tried adding it as an inline style, but the raw style is showing up on the page. I feel like I'm missing something easy
http://imgur.com/kkATCAC
<?php
// Custom loop that adds a clearing class to the first item in each row
$args = array('numberposts' => -1, 'order' => 'ASC' ); //For this example I am setting the arguments to return all posts in reverse chronological order. Odds are this will be a different query for your project
$allposts = get_posts($args);
$numCol = 2; // Set number of columns
$thumbnail = get_the_post_thumbnail( $page->ID, 'thumbnail' );
// Start Counter
$counter = 0;
foreach ($allposts as $post) {
$content = '<div class="col-md-6 columns-'.$numCol.($counter % $numCol == 0 ? ' first' : '').'" style="background: url("${thumbnail}") center center/cover no-repeat;">'; // Add class to first column
$content .= '<h3>'.$post->post_title.'</h3>';
$content .= $post->post_content;
$content .= '</div>';
echo $content;
$counter ++;
}
?>
UPDATE 2
I've checked the quotes but now I'm getting a parse error and the page doesn't load at all.
$content = '<div style="background: url('${thumbnail}') center center/cover no-repeat;" class="col-md-6 columns-'.$numCol.($counter % $numCol == 0 ? ' first' : '').'">'; // Add class to first column

Answer 1

You could add it as an inline style:
<?php
$thumbnail = get_the_post_thumbnail( $page->ID, 'thumbnail' );
$content = "<div class='your-post-thing' style='background: url('${thumbnail}') center center/cover no-repeat;'>...stuff...</div>';
echo $content;
?>
OR
Depending on your browser support, you could use object-fit:
<?php
$content .= "<div class='your-post-thing'>";
$content .= "<img class='background-image' src='${thumbnail}' />";
$content .= "</div>";
echo $content;
?>
CSS:
.your-post-thing {
position: relative;
}
.background-image {
position: absolute;
top: 0;
left: 0;
width: 100%;
height: 100%;
object-fit: cover;
}

Answer 2

$content = '<div style="background-image:url('.wp_get_attachment_url(get_the_post_thumbnail()).')" class="col-md-6 columns-'.$numCol.($counter % $numCol == 0 ? ' first' : '').'">'; // Add class to first column
you can try something like this, and in your css you can add the rules to view correctly the background.