text only post affecting sidebar

When I view a single post on my site (single.php) my sidebar drops down. My posts are text only and have no images, and the two columns are narrow enough to not be causing it. My site is 800px wide and my sidebar is 230px, and even if I make my left column 400px, it still does it. Any ideas?

Screenshot: https://www.crawlmag.com/screen2.jpg

My CSS… (please do not delete my post, this is NOT too much code, it is the necessary code required of me to get help LOL

Single.php

<?php get_header(); ?>
<div id="post_leftcol">

<?php if (have_posts()) : while (have_posts()) : the_post(); ?>
<div class="post_leftcol_entry">
<div class="post" id="post-<?php the_ID(); ?>">
<h2><?php the_title(); ?></h2>

<?php the_content('<p class="serif">Read the rest of this page &raquo;
'); ?>

<?php wp_link_pages(array('before' => '<strong>Pages:</strong> ', 'after' => '
', 'next_or_number' => 'number')); ?>

</div>
</div>
<?php endwhile; endif; ?>
<?php edit_post_link('Edit this entry.', '', '
'); ?>
</div>

<?php get_sidebar(); ?>

<?php get_footer(); ?>

CSS StyleSheet
`#post_leftcol
{
width: 500px;
margin: 0 0 0 7px;
background: #fff;
}

#post_leftcol__entry
{
width:480px;
float:left;
margin:6px 0 0 0;
font-family: Verdana, Arial, Helvetica, sans-serif;
font-size: 10px;
text-align:justify;
padding:0;
background: #fff;
}

#sidebar
{
width:230px;
float:right;
margin:5px;
padding:0;
}