first excerpt fine, subsequent post excerpts shift to the right instead of displaying vertically [closed]

I can’t add comments yet, but do you get what Milo is saying?

Just look at this section and it is as if there are no closing or tags for the classes post and post-preview.

            <?php if ( have_posts() ) : while ( have_posts() ) : the_post(); ?>
            <div class="post-image">
                <?php
                    if ( has_post_thumbnail() ) {
                        the_post_thumbnail( 'custom-image' );
                    }
                ?>
            </div>
            <div class="post">
                <h2><?php the_title() ;?></h2>
                <span class="post-preview">
                    <?php the_excerpt('read more...'); ?>
                            <?php endwhile; else: ?>