Space between two div's, help me remove it.

I’ve tried everything but can’t seem to find how to remove a space between two div’s on my wordpress.

I have higlighted the div with a yellow border so you can easely see what I mean.

The strange thing is that the space only appears on single post’s.
See https://masteecate.com/?p=7

If you go back to the main page (click the logo) you can see the yellow box at the bottom with no space under it.

This is my main index template:

<?php get_header(); ?> 

              <ul class="mcol">
              <?php if(have_posts()) : ?><?php while(have_posts()) : the_post(); ?>
              	<li class="article">

                    	<?php
                    	if ( has_post_thumbnail() ) { ?>
                    	<?php
                    	$imgsrcparam = array(
						'alt'	=> trim(strip_tags( $post->post_excerpt )),
						'title'	=> trim(strip_tags( $post->post_title )),
						);
                    	$thumbID = get_the_post_thumbnail( $post->ID, 'background', $imgsrcparam ); ?>
                        <div><a href="<?php the_permalink() ?>" class="preview"><?php echo "$thumbID"; ?></a></div>
                    	<?php } ?>

                    <h2><a href="<?php the_permalink(); ?>" title="<?php the_title(); ?>"><?php the_title(); ?></a></h2>
                    <?php the_excerpt(); ?>
                    <div class="postmetadata">
			<!-- By: <?php the_author_posts_link(); ?><br /> -->
                        <?php the_time(__('F jS, Y', 'kubrick')) ?>&nbsp;ˑ&nbsp;
                        <?php comments_popup_link(__('No Comments'), __('1 Comment'), __('% Comments'), '', __('Comments Closed') ); ?><br />
                        <?php printf(__('Category: %s'), get_the_category_list(', ')); ?>
                    </div>
                </li>
            <?php endwhile; ?>
            <?php else : ?>
            <?php endif; ?>
            </ul>

            <?php if(have_posts()) : ?><?php while(have_posts()) : the_post(); ?>
            <?php endwhile; ?>
            <?php else : ?>
            <div id="main">
                <h1><?php _e("Sorry, but you are looking for something that isn’t here."); ?></h1>
            </div>
            <?php endif; ?>

            <?php if(have_posts()) : ?><?php while(have_posts()) : the_post(); ?>
            <?php endwhile; ?>
                <div id="nav">
                    <div id="navleft"><?php next_posts_link(__('Previous page&nbsp;')) ?></div>
                    <div id="navright"><?php previous_posts_link(__('Next page&nbsp;')) ?></div>
                </div>
            <?php else : ?>
            <?php endif; ?>

<?php get_footer(); ?>

And this is my single post

<?php get_header(); ?> 

<?php get_sidebar(); ?> 

            <div id="main-inner">

              <?php if(have_posts()) : ?><?php while(have_posts()) : the_post(); ?>
                <div class="article" id="post-<?php the_ID(); ?>">

                      <h1><?php the_title(); ?></h1>
                      <div class="postmetadata">
                         <!-- By: <?php the_author_posts_link(); ?>&nbsp;ˑ&nbsp; --> <?php the_time(__('F jS, Y')) ?>&nbsp;ˑ&nbsp;<?php printf(__('Category: %s'), get_the_category_list(', ')); ?>&nbsp;ˑ&nbsp;
                          <?php comments_popup_link(__('No Comments'), __('1 Comment'), __('% Comments'), '', __('Comments Closed') ); ?><?php edit_post_link(__('Edit this entry'), '&nbsp;ˑ&nbsp;', ''); ?>
                      </div>
                      <?php the_content(); ?>
                      <div class="postmetadata tags">
					  		<?php the_tags(); ?>
                      </div>

                </div>

            <?php endwhile; ?>

                <div id="nav">
                    <div id="navleft"><?php previous_post_link('%link', 'Previous article'); ?></div>
                    <div id="navright"><?php next_post_link('%link', 'Next article'); ?></div>
                </div>

<?php comments_template(); ?>

            <?php else : ?>
                <h1><?php _e("Sorry, but you are looking for something that isn’t here."); ?></h1>
            <?php endif; ?>

            </div>

<?php get_footer(); ?>

If you need any more code, please tell me.
Thanks!