Is it possible to show only node contents in shadowbox pages?
For Drupal7:

Add to your theme template.php (or add inner of function code to existing function prepropress_page closer to the end) next function:

/**
 * Override or insert variables into the page templates.
 */
function YOURTHEME_preprocess_page(&amp;$vars, $hook) {
  if (isset($_GET['shadow']) &amp;&amp; $_GET['shadow']) {
    $vars['theme_hook_suggestions'][] = 'page__empty';
  }
}


Add page--empty.tpl.php to your theme folder - take original copy from page.tpl.php, but remove printing all header, sidebars, footer regions. E.g.:

&lt;?php
/**
 * @file
 * Returns the HTML for Drupal page only with content region = empty page.
 */
?&gt;
&lt;?php if ($title): ?&gt;
  &lt;h1 class="page__title title" id="page-title"&gt;&lt;?php print $title; ?&gt;&lt;/h1&gt;
&lt;?php endif; ?&gt;
&lt;?php print render($page['content']); ?&gt;


Make shadowbox scripts added to any page (shadowbox ui settings), and you can do next anywhere:

&lt;a href="/node/1?shadow=1" rel="shadowbox" title="About"&gt;About&lt;/a&gt;


So, any link with url?shadow=1 and rel="shadowbox" will shown on shadowbox popup window only content without sidebars. Control size of window on rel="shadowbox" as documented.

For shadowbox links that generated automatically (views, fields) you should override it via settings or template.