Thanks, Norcross! Worked like a charm. For others that are interested, what I did is this:
1. Replace the <body>
tag in the header file with <body <?php body_class(); ?>>
2. Replace the postentry div class in the index.php, single.php, category.php, etc. (for consistency) with <div id="post-<?php the_ID(); ?>" <?php post_class('postentry'); ?>>
3. Added the following styling to my CSS file,
#postarea .category-links h2 {font-size:20pt;}
#postarea .category-links h2 a {font-size:20pt;}
#postarea .category-links p {font-size:13pt; line-height:15pt}
Hope that helps someone else and thanks again Norcross!