I've been hammering this question out over at stackoverflow with some folks: http://stackoverflow.com/questions/7478500/jquery-or-css-problem

Take a look here to see the problem: http://themeforward.com/demo2/2011/01/17/testing-comments/comment-page-1/#comments

I am using a javascript to make the height of #post_content and #sidebar match. I have figured out the problem is it works perfectly, but once the comments template is added to my single-post.php it all falls apart and the heights no longer match (as shown in the link). What do I have to do to make this code realize comments.php is wrapped by post_content!?

Here is my javascript:

<script type='text/javascript'>
function resizeIt() {
  console.log("post_content.outerheight: " + $('#post_content').height() + ", sidebar.height: " + $('#sidebar').height());
  if($('#post_content').outerHeight(true) > $('#sidebar').height()) {
      $('#sidebar').height($('#post_content').outerHeight(true)+'px');
   }
}

$(document).ready(function() {
  resizeIt();
  $('#post_content').resize(resizeIt());
});
</script>

CSS that may/may not play a role:

#container {
  width: 1126px;
  clear: both;
  overflow: hidden;
}
#post_content {
  clear: both;
  display: block;
  float: left;
  overflow: hidden;
  width: 660px;
  background-color: #FF0000;
}
#sidebar {
  display: inline-block;
  float: right;
  width: 410px;
  overflow: hidden;
  background-color: #0000FF;
}
#respond {
	clear:both
}
#commentlist {
	list-style:none;
	width:100%
}

My markup:

<?php get_header(); ?>

<div id="container">
<div id="post_content">




<!-- Grab posts -->
<?php if (have_posts()) : ?><?php while (have_posts()) : the_post(); ?>

<!-- Breadcrumbs -->
<?php if (function_exists('dimox_breadcrumbs')) dimox_breadcrumbs(); ?>

<!-- Avatar -->
<span class="post_avatar">
	<a href="<?php echo get_bloginfo('url') . '/author/' . get_the_author_meta('login'); ?>">
	<?php echo get_avatar( get_the_author_email(), '50' ); ?>
	</a>
</span>

<!-- Title -->
<h1 class="post">
	<?php the_title(); ?>
</h1>

<!-- Post time, author, category -->
<span class="sub-title-post">By <?php the_author_posts_link( ); ?> <span class="sub-title-divider">|</span> <?php the_time('F j, Y'); ?> <span class="sub-title-divider">|</span> <a href="#commentlist"><?php comments_number( 'No comments', 'One comment', '% comments' ); ?></a>
</span>


<!-- The post -->
<?php the_content(); ?>

<!-- Tags -->
<div class="tag_spacer">

	<h3 class="tags">
	<?php the_tags('Tags ',' / ','<br />'); ?>
	</h3>

	<h3 class="tags">
	<?php $turl = getTinyUrl(get_permalink($post->ID));
echo 'Short URL <a href="'.$turl.'">'.$turl.'</a>' ?>
	</h3>
</div>


<!-- Next/Previous Posts -->
<div class="mp_archive2">
<div id="more_posts">
	<div class="oe">
		<?php previous_post_link('%link', '« Previous post', TRUE); ?>
	</div>

	<div class="re">
		<?php next_post_link('%link', 'Next post »', TRUE); ?>
	</div>
</div>
</div>

<?php comments_template(); ?>

</div>


<?php endwhile; else: ?>
<p>No matching entries found.</p>
<?php endif; ?>

<?php get_sidebar(); ?>
</div>
</div>
</div>
<?php get_footer(); ?>