title: Setting the_post_thumbnail width to 100%
body: <p>How to set <code>the_post_thumbnail</code> so that it doesn't use an array for its size, but instead can be set with a 100% width and auto height:</p>
  
  <pre><code>&lt;?php $ht_featured_img = get_option('ht_featured_img'); 
  if ($ht_featured_img == "true") { ?&gt;
      &lt;?php if (  (function_exists('has_post_thumbnail')) &amp;&amp; (has_post_thumbnail())  ) { /* if post has a thumbnail */ ?&gt;
          &lt;div class="post-image"&gt;
              &lt;?php the_post_thumbnail( array(1215,9999) ); ?&gt;
          &lt;/div&gt;&lt;!--post-image--&gt;
      &lt;?php } ?&gt;
  &lt;?php } ?&gt;
  </code></pre>