Revised: post_title.php

<?php if(is_page()) : ?>
    <h2 class="art-postheader" style="display:none !important;">
        <a href="<?php echo $post_link; ?>" rel="bookmark" title="<?php echo $post_link_title; ?>"><?php echo $post_title; ?></a>
    </h2>
<?php else : ?>
    <h2 class="art-postheader">
        <a href="<?php echo $post_link; ?>" rel="bookmark" title="<?php echo $post_link_title; ?>"><?php echo $post_title; ?></a>
    </h2>
<?php endif; ?>