Wordpress CSS problem

Hi, I have a small problem with my CSS on a wordpress theme. The problem I have is in both Firefox and Internet Explorer when more than 1 post is added the sidebar drops below the content.

This is my CSS:

#content {
	width: 650px;
	float: left;
	min-height: 100%;
	margin-bottom: 20px;
	margin-top: 20px;
	text-align: left;
	padding: 10px; 
}
#content h2 {
	margin: 0em 0em 0em;
	padding: 0em;
	font-size: 16px
	margin-top: -0px;
}
#content .post {
	margin: 0em 0em 0em;
	padding-left: 10px;
	padding-right: 10px;
}
#content .post h2 {
	font-size: 26px;
	margin-top: -0px;
}
#content h3 {
	margin: 0em;
	padding: 0em;
	font-size: 26px;
}
#content .postmetadata {
	color: #777777;
	background: inherit;
	font-size: 12px;
}
#content .navigation {
	margin: 2em 0em 0em;
	padding: 0em;	
	display: block;
}
#content .goback {
	margin: 0em 0.5em 0em 0em;
	padding: 0em;
	float: left;
	font-size: 1.25em;
}
#content .goforward {
	margin: 0em 0em 0em 0.5em;
	padding: 0em;
	float: right;
	font-size: 1.25em;
}
#content #comments {
	margin: 2em 0em 1em;
	padding: 0em;
	clear: both;
}
#content .commentlist {	
	margin: 0em;
	padding: 0em;
	font-size: 0.9em;
}
#content .commentlist li {
	margin: 0em;
	padding: 0em;
	list-style-type: none;
}
#content .commentlist img.avatar {
	float: right;
	margin-left: 1em;
}
#content .commentmetadata {
	margin: 0em 0em 2em;
	color: #777777;
	background: inherit;
}
#content #respond {
	margin: 2em 0em 1em;
	padding: 0em;
	clear: both;
}
#sidebar {
	margin-left: 10px;
	width: 230px;
	float: left;
	min-height: 100%;
	margin-bottom: 20px;
	margin-top: 60px;
	text-align: left;
}
#sidebar a {
	font-size: 14px;
}
#sidebar h2 {
	margin: 0em;
	padding: 0em;
	font-size: 14px;
}
#sidebar h2 a, #sidebar h2 a:visited {
	color: black;
	background: inherit;
}
#sidebar h2 a:hover {
	color: white;
	background: #1070c0;
}
#sidebar ul {
	margin: 0em;
	padding: 0em;
}
#sidebar ul li {
	margin: 0em 0em 1em;
	padding: 0em;
	
	list-style-type: none;
}
#sidebar ul li p, #sidebar ul li ul, #sidebar ul li ol {
	font-size: 0.8em;
}
#sidebar ul li ul li, #sidebar ul li ol li {
	margin: 0em;
	padding: 0em;
}
#sidebar .textwidget {
	font-size: 0.8em;
}

Code (markup):

This is my index page:

<?php get_header(); ?>

<?php /* this is to deal with author pages */
if(isset($_GET['author_name'])) :
$curauth = get_userdatabylogin($author_name); // NOTE: 2.0 bug requires get_userdatabylogin(get_the_author_login());
else :
$curauth = get_userdata(intval($author));
endif;
?>
<div id="content">

	<?php if (have_posts()) : ?>
		
		<?php if (!is_single() && !is_page()) echo "<h2 class=\"pagetitle\">";
		if (is_home()) {
			
		} elseif (is_category()) {
			echo 'Posts categorized &#8220;' . single_cat_title('', false) . '&#8221;';
		} elseif (is_tag()) {
			echo 'Posts tagged  &#8220;' . single_tag_title('', false) . '&#8221;';
		} elseif (is_author()) {
			echo 'Posts by ' . $curauth->nickname;
		} elseif (is_day()) {
			echo 'Posts from ' . get_the_time('M jS, Y');
		} elseif (is_month()) {
			echo 'Posts from ' . get_the_time('M Y');
		} elseif (is_year()) {
			echo 'Posts from ' . get_the_time('Y');
		} elseif (is_time()) {
			echo 'Posts from a particular time on ' . get_the_time('M, jS, Y');
		} ;
		if (!is_single() && !is_page()) echo "</h2>"; ?>

		<?php while (have_posts()) : the_post() ?><div class="npost">
		<div id="toppost"><h2 class="pagetitle"><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title_attribute(); ?>"><?php the_title(); ?></a></h2></div>
		<div id="topdate"><?php the_time('jS')?><br/><?php the_time('M')?><br/><?php the_time('Y')?></div>
		<div id="midpost">
		<?php if (is_single() || is_page()) { /* for single-item pages, make that thing big */ ?>
			<div class="post" id="post-<?php the_ID(); ?>">
		<?php } else { /* otherwise, make it small since you'll have one of the headings above */ ?>
			<div class="post" id="post-<?php the_ID(); ?>">
				
			<?php } ?>
				<div class="entry">
					<?php the_content('More... &raquo;'); ?>
				</div>
				
				<?php if (is_single() || is_page()) { ?>
					<?php wp_link_pages(array('before' => '<p><strong>Pages:</strong> ', 'after' => '</p>', 'next_or_number' => 'number')); ?>
				<?php } ?>
				<p class="postmetadata">Posted by <?php the_author_posts_link(); ?> in <?php /* pages don't have categories or tags */ if (!is_page()) { ?> <?php the_category(', '); ?>. <?php /* } */?> at <?php the_time('g:i a'); ?> on <?php the_time('jS M Y')?>. <?php edit_post_link('Edit this post.', '(', ')'); ?> <?php comments_popup_link('No comments... &#187;', '1 comment... &#187;', '% comments... &#187;', 'comments-link', ''); ?><?php if (get_the_tags()) the_tags('Tags: ', ', ', '.'); ?><?php } ?></p>
				
		<?php comments_template(); ?>
		</div></div><div id="botpost"></div>
		<?php endwhile; ?>
</div>	
		<?php if (!is_single() && !is_page()) { ?>
			<div class="navigation">
						<div class="goback"><?php next_posts_link('&laquo; Back...'); ?></div>
						<div class="goforward"><?php previous_posts_link('Forward... &raquo;'); ?></div>
			</div>
		<?php } ?>

	<?php else : ?>

		<h2>Not Found</h2>
		<p>Sorry, but you are looking for something that isn't here.</p>

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

<?php get_footer(); ?>

Code (markup):

Could anyone help me out with this please? Thanks.

 

Simply share the URL coz Live editing would make things much more easier.

Thanks.

 

May by this is your problem?

Like simpleloveman said share URL if you need help.