Grid Layout mit Flexbox: WordPress Loop

archive.php

<?php
/**
 * The template for displaying archive pages
 */

get_header(); ?>

	<div id="primary" class="content-area">
		<main id="main" class="site-main" role="main">

		<?php if ( have_posts() ) : ?>

			<header class="page-header">
				<?php the_archive_title( '<h1 class="page-title">', '</h1>' ); ?>
			</header><!-- .page-header -->

			<div class="post-wrapper">

				<?php
				while ( have_posts() ) : the_post();

					get_template_part( 'template-parts/content' );

				endwhile;
				?>

			</div>

		<?php endif; ?>

		</main><!-- .site-main -->
	</div><!-- .content-area -->

<?php get_sidebar(); ?>
<?php get_footer(); ?>

content.php

<?php
/**
 * The template part for displaying content
 */
?>

<div class="post-column">

	<article id="post-<?php the_ID(); ?>" <?php post_class(); ?>>

		<header class="entry-header">
			<?php the_title( sprintf( '<h2 class="entry-title"><a href="%s" rel="bookmark">', esc_url( get_permalink() ) ), '</a></h2>' ); ?>
		</header><!-- .entry-header -->

		<?php the_post_thumbnail(); ?>

		<div class="entry-content">
			<?php the_content( esc_html__( 'Read more', 'theme-slug' ) ); ?>
		</div><!-- .entry-content -->

	</article><!-- #post-## -->

</div>