Create related posts section in Genesis Framework using ACF

single.php

<?php

add_action( 'genesis_before_comments', 'io_related_posts' );
function io_related_posts() {
	$relatedPosts = get_field( 'related_posts' );

		if( $relatedPosts ): 
			echo '<div class="related-posts-container">';
			echo '<h3>Related Posts</h3>';
			echo '<ul class="related-posts">';
				foreach( $relatedPosts as $relatedPost ): // variable must NOT be called $post (IMPORTANT) 
			    echo '<li>';
			    	echo '<a href="' . get_permalink( $relatedPost->ID ) . '">' . get_the_post_thumbnail( $relatedPost->ID ) .'<h5>' . get_the_title( $relatedPost->ID ) . '</h5></a>';
			    	echo wp_trim_words( get_the_content( $relatedPost->ID ), 20, null );
			    echo '</li>';
				endforeach;
			echo '</ul>';
			echo '</div>';
		endif;
}

genesis();

style.css

.related-posts-container {
  background-color: #fff;
  font-size: 18px;
  font-size: 1.8rem;
  margin-bottom: 40px;
  padding: 60px;
}

.related-posts-container h3 {
  margin-bottom: 5%;
}

.related-posts {
  display: -webkit-box;
  display: -ms-flexbox;
  display: flex;
  -ms-flex-flow: row wrap;
      flex-flow: row wrap;
  -webkit-box-pack: justify;
      -ms-flex-pack: justify;
          justify-content: space-between;
}

.related-posts li {
  -ms-flex-preferred-size: 32%;
      flex-basis: 32%;
}

@media only screen and (max-width: 450px) {
  .related-posts li {
    -ms-flex-preferred-size: 100%;
        flex-basis: 100%;
    margin-bottom: 10%;
  }
}