Problem of line spacing in categories list (sidebar)

I have a problem with my sidebar categories appearance but only in Internet Explorer and not in Firefox. I didn’t specially customized the look of the wp_list_categories list in css. I just would like this categories list look like the latest posts list in Internet Explorer. Do you know what is causing this ? Here is how it looks like.

On my site
Screenshot

In sidebar.php

<li><h2>Categories</h2>
   <ul>
      <?php wp_list_categories('show_count=1&amp;feed_image=https://www.webtricksbox.com/wp-content/themes/blueprolarge/images/feed-icon.gif&amp;title_li='); ?>
   </ul>
</li>

<li><h2>Latest Posts</h2>
   <ul>
      <?php wp_get_archives('type=postbypost&amp;limit=10'); ?>
   </ul>
</li>

<?php if (function_exists('get_most_viewed')): ?>
<li><h2>Most Viewed Posts</h2>
   <ul>
      <?php get_most_viewed('post', 10); ?>
   </ul>
</li>
<?php endif; ?>

In style.css

#sidebar{float:left;width:350px;margin:0px;padding:0px;font: 11px Verdana;padding-bottom:10px;}
.rsidebar{font: 11px  Verdana;color:#808080;float:right;width:350px;}
.rsidebar h2{margin-top:20px;margin-bottom:5px;font: 11px Verdana;color:#FFFFFF;font-weight:bold;padding:0;line-height:30px;padding-left:16px;background:url('images/sidebarh2bg.gif') repeat-x;text-transform:uppercase;}
.rsidebar a {font-weight:normal;}
.rsidebar ul{list-style-type:none;margin:0;padding:0;float:left;}
.rsidebar ul li{list-style-type:none;margin:0 0 0px;padding:0;float:left;width:350px;}
.rsidebar ul li ul{list-style-type:square;margin:0px;padding:0px;padding-bottom:3px;}
.rsidebar ul li ul li{list-style-type:none;margin:0;line-height:25px;width:334px;padding-left:16px;}
.rsidebar ul li ul li a {font:11px Verdana;font-weight:normal;color:#054474;line-height:25px;}
.rsidebar ul li ul li a:visited {color:#054474;font-weight:normal;}
.rsidebar ul li ul li a:hover {text-decoration:none;}
.rsidebar ul li ul li a:visited:hover {text-decoration:none;}

The HTML source overview of the result

<li><h2>Categories</h2>

   <ul>
	<li class="cat-item cat-item-13"><a href="https://www.webtricksbox.com/category/apache/" rel="nofollow" title="View all posts filed under Apache">Apache</a> <a href="https://www.webtricksbox.com/category/apache/feed/" rel="nofollow"><img src="https://www.webtricksbox.com/wp-content/themes/blueprolarge/images/feed-icon.gif" alt="Feed for all posts filed under Apache"></a> (1)
</li>
	<li class="cat-item cat-item-3"><a href="https://www.webtricksbox.com/category/seo/" rel="nofollow" title="View all posts filed under SEO">SEO</a> <a href="https://www.webtricksbox.com/category/seo/feed/" rel="nofollow"><img src="https://www.webtricksbox.com/wp-content/themes/blueprolarge/images/feed-icon.gif" alt="Feed for all posts filed under SEO"></a> (1)

</li>
   </ul>
</li>

<li><h2>Latest Posts</h2>
   <ul>
	<li><a rel="nofollow" href="https://www.webtricksbox.com/advanced-htaccess-tricks-for-securing-sites/" title="Advanced .htaccess Tricks for Securing Sites">Advanced .htaccess Tricks for Securing Sites</a></li>
	<li><a rel="nofollow" href="https://www.webtricksbox.com/seo-guide-in-7-steps/" title="SEO Guide in 7 steps">SEO Guide in 7 steps</a></li>
   </ul>

</li>

<li><h2>Most Viewed Posts</h2>
   <ul>
      <li><a href="https://www.webtricksbox.com/advanced-htaccess-tricks-for-securing-sites/" title="Advanced .htaccess Tricks for Securing Sites">Advanced .htaccess Tricks for Securing Sites</a> (50)</li>
      <li><a href="https://www.webtricksbox.com/seo-guide-in-7-steps/" title="SEO Guide in 7 steps">SEO Guide in 7 steps</a> (42)</li>   </ul>

</li>

I do my best to learn quickly but my lack of knowledge is huge. Any help to understand the origin of this problem would be welcome.