You must build a correct hierarchy of classes. Nest classes like:
<div class="hentry">
<h1 class="entry-title"></h1>
<div class="entry">
<span class="updated">Date</span>
</div>
</div>
This is my full single.php:
<?php get_header(); ?>
<section class="content">
<?php get_template_part('inc/page-title'); ?>
<div class="pad group">
<?php while ( have_posts() ): the_post(); ?>
<article <?php post_class(); ?>>
<div class="post-inner group">
<h1 class="post-title entry-title"><?php the_title(); ?></h1>
<p class="post-byline"><?php _e('by','hueman'); ?>
<span class="vcard author"><span class="fn">
<a href="https://plus.google.com/+HeikkiLahtela" target="_blank" rel="author"><?php the_author() ?></a>
</span></span> · <span class="updated"><?php the_time('F j, Y'); ?></span></p>
<?php get_template_part('inc/post-formats'); ?>
<div class="clear"></div>
<div class="entry">
<div class="entry-inner">
<div class="entry-content"><?php the_content(); ?></div>
<p class="post-byline"><?php _e('by','hueman'); ?>
<span class="vcard author"><span class="fn">
<a href="https://plus.google.com/+HeikkiLahtela" target="_blank" rel="author"><?php the_author() ?></a>
</span></span>
· Last modified <span class="updated"><?php the_modified_date('F j, Y'); ?></span></p>
<?php wp_link_pages(array('before'=>'<div class="post-pages">'.__('Pages:','hueman'),'after'=>'</div>')); ?>
</div>
<div class="clear"></div>
<?php the_tags('<p class="post-tags"><span>'.__('Tags:','hueman').'</span> ','','</p>'); ?>
</div><!--/.entry-->
</div><!--/.post-inner-->
</article><!--/.post-->
<?php endwhile; ?>
<div class="clear"></div>
<?php //the_tags('<p class="post-tags"><span>'.__('Tags:','hueman').'</span> ','','</p>'); ?>
<?php if ( !ot_get_option( 'author-bio' ) && get_the_author_meta( 'description' ) ): ?>
<div class="author-bio">
<div class="bio-avatar"><?php echo get_avatar(get_the_author_meta('user_email'),'128'); ?></div>
<p class="bio-name"><?php the_author_meta('display_name'); ?></p>
<p class="bio-desc"><?php the_author_meta('description'); ?></p>
<div class="clear"></div>
</div>
<?php endif; ?>
<?php if ( ot_get_option( 'post-nav' ) == 'content') { get_template_part('inc/post-nav'); } ?>
<?php if ( ot_get_option( 'related-posts' ) != '1' ) { get_template_part('inc/related-posts'); } ?>
<?php comments_template('/comments.php',true); ?>
</div><!--/.pad-->
</section><!--/.content-->
<?php get_sidebar(); ?>
<?php get_footer(); ?>
Did this work?