Moving from bootstrap html to wordpress

I am installing a simple bootstrap website in wordpress (the original bootstrap website came in html and I addapted it to the wordpress). Everything was ok until I created the loop in the index.php file. The Website now looks a little different from the original. The code in the index file is:

url wordpress https://ashtangafaro.com/wpnovo/
url original https://www.w3schools.com/bootstrap/trybs_theme_me_complete.htm

<?php get_header(); ?>

<?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
<?php the_content(); ?>
<?php endwhile; else: ?>
<p><?php _e('Sorry, no posts matched your criteria.'); ?></p>
<?php endif; ?>

<?php get_footer(); ?>