Firefox 3 — strange image/title spacing in a post query list / array

I am using the below code in my site https://www.musikmodem.com in order to call up a list of three posts from the ‘features’ category, and display their titles along with an associated image for each post.

Between the bottom of the associated image and the title of the post, there are 8px when viewing the site with MSIE 7 and FF2 — but in FF3, there are only 7px between the image and title of the second item on the list (and still 8px between the image and title of the first and third items on the list).

Why would FF3 make such a bizarre display error? Any clues?

<div id="leftcol">
<?php query_posts('showposts=3&cat=5'); ?>
<h3>
<?php wp_list_categories('include=5&title_li=&style=none'); ?>
</h3>
<?php while (have_posts()) : the_post(); ?>
<div class="feature">
<a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title(); ?>"><img src="<?php bloginfo('template_url'); ?>/images/feature-thumbs/<?php $values = get_post_custom_values("Image"); echo $values[0]; ?>" alt="" /></a>
<a href="<?php the_permalink() ?>" rel="bookmark" class="title"><?php the_title(); ?></a>
</div>
<?php endwhile; ?>