How to add bootstrap grid layout to search.php - php

Question

I am trying to have the layout of my posts on my search results be 2 posts per line. Right now there is 1 post, so I am trying to add in 'col-sm-6 col-md-6' to my search.php file. However, every time I try to add it in nothing changes. Does anyone have any solutions?
search.php
<?php get_header(); ?>
<div id="page">
<div class="column span-9 first" id="maincontent">
<div class="content">
<?php if (have_posts()) : ?>
<form role="search" method="get" class="search-form-search form-inline-search" action="">
<div class="input-group-search">
<input type="search" value="" name="s" class="input-sm-search search-field-search form-control-search" placeholder="<?php echo $s ?>">
</div>
</form>
<div class="clear"></div>
<?php while (have_posts()) : the_post(); ?>
<div class="search-post" id="post-<?php the_ID(); ?>">
<?php the_post_thumbnail('full', array('class' => 'medium-front-thumbnail')); ?>
<div class="front-page-date"><?php echo human_time_diff( get_the_time('U'), current_time('timestamp') ) . ' ago'; ?></div>
<h2><a class="front-page-post-title" href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
<p class="front-page-post-excerpt"><?php echo get_the_excerpt(); ?></p>
<div class="front-page-post-info">
<a class="moretext" href="<?php the_permalink(); ?>">Read more</a>
<?php get_template_part( 'front-shop-the-post' ); ?>
<?php get_template_part( 'share-buttons' ); ?>
<div class="front-comments"><?php comments_popup_link ('0', '1', '%', 'comment-count', 'none'); ?></div>
</div>
</div>
<?php endwhile; ?>
<?php else : ?>
<h2 class="center">No posts found. Try a different search?</h2>
<?php include (TEMPLATEPATH . '/searchform.php'); ?>
<?php endif; ?>
</div> <!-- /content -->
</div> <!-- /maincontent-->
</div> <!-- /page -->
<?php get_footer(); ?>
Here is another version of a search.php I have been playing around with. However, with this one the web page doesn't show up.
<?php
get_header();
$the_query = new WP_Query( [
'posts_per_page' => 15,
'paged' => get_query_var('paged', 1)
] );
if ( $the_query->have_posts() ) { ?>
<div id="ajax">
<?php
while ( $the_query->have_posts() ) { $the_query->the_post(); ?>
<div class="row">
<article <?php post_class( 'col-sm-6 col-md-6' ); ?>>
<div class="large-front-container">
<?php the_post_thumbnail('full', array('class' => 'large-front-thumbnail')); ?>
</div>
<div class="front-page-date"><?php echo str_replace('mins', 'minutes', human_time_diff( get_the_time('U'), current_time('timestamp') ) . ' ago'); ?></div>
<h2><a class="front-page-post-title" href="<?php the_permalink(); ?>"><?php the_title(); ?></a></h2>
<p class="front-page-post-excerpt"><?php echo get_the_excerpt(); ?></p>
<div class="front-page-post-info">
<a class="moretext" href="<?php the_permalink(); ?>">Read more</a>
<?php get_template_part( 'front-shop-the-post' ); ?>
<?php get_template_part( 'share-buttons' ); ?>
<div class="front-comments"><?php comments_popup_link ('0', '1', '%', 'comment-count', 'none'); ?></div>
</div>
</article>
</div>
<?php if(get_query_var('paged') < $the_query->max_num_pages) {
}
}
elseif (!get_query_var('paged') || get_query_var('paged') == '1') {
echo '<p>Sorry, no posts matched your criteria.</p>';
}
wp_reset_postdata();
get_footer();