Verticle line/gap required on main index page

Hello there. I have 2 columns of posts on my main index page. The problem being, as you’ll see, that left and right had posts are very close to one another.

Can anyone provide any advice on how I can either add a gap between the two columns or add a verticle line of some sort between the left/right hand columns.

You can view my site at https://www.snowmenu.com

Just to let you know, I used this code to add the columns. I have this in stylesheet.

/* columns */
div.post-block {
width: 280px;
float: left;
clear: none;
}
div#container_division {
width: 585px;
}

I then have this within the main index.

<div class=”post-block”>
<div class=”solidline margintop”></div>
<h3>“><?php the_title(); ?></h3>
<?php get_the_image( array( ‘meta_key’ => ‘feature_img’, ‘size’ => ‘small’, ‘width’ => ‘150’, ‘height’ => ‘100’, ‘image_class’ => ‘feature’ ) ); ?>

” title=”Read more on <?php the_title(); ?>” class=”more-link”>Read more on <?php the_title(); ?>

Category: <?php the_category(‘, ‘) ?>

<?php tweet_this_manual(); ?>
</div>

<?php endwhile; else: ?>
<?php endif; ?>
</div>

I would really appreciate any help from anyone on this. Afraid I am a little out of my depth now. Many thanks.