title: Including CSS file to mpdf
body: <p>I am trying to implement a CSS file to my mPDF file. Here is my mPDF file:</p>
  <pre><code>    $pdf_output = '&lt;!DOCTYPE html PUBLIC &quot;-//W3C//DTD XHTML 1.1//EN&quot; &quot;http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd&quot;&gt;
          &lt;html xml:lang=&quot;en&quot;&gt;
  
          &lt;head&gt;
              &lt;meta http-equiv=&quot;Content-Type&quot; content=&quot;text/html; charset=UTF-8&quot; /&gt;
              &lt;title&gt;' . get_bloginfo() . '&lt;/title&gt;';
  
      $cssFile = __DIR__.DIRECTORY_SEPARATOR.'styles.css';
  //   echo $cssFile;
      if (file_exists($cssFile)) {
          $pdf_output .= '&lt;style type=&quot;text/css&quot;&gt;'.file_get_contents($cssFile).'&lt;/style&gt;';
      }
  
      $pdf_output .= '&lt;/head&gt;
          &lt;body xml:lang=&quot;en&quot;&gt;
              &lt;pagebreak&gt;
              &lt;div id=&quot;header&quot;&gt;&lt;div id=&quot;headerimg&quot;&gt;
                  &lt;h1&gt;&lt;a href=&quot;' . get_option('home') . '/&quot;&gt;' .  get_bloginfo('name') . '&lt;/a&gt;&lt;/h1&gt;
                  &lt;div class=&quot;description&quot;&gt;' .  get_bloginfo('description') . '&lt;/div&gt;
              &lt;/div&gt;
              &lt;/div&gt;
              &lt;div id=&quot;content&quot; class=&quot;widecolumn&quot;&gt;&lt;div id=&quot;test&quot;&gt;Lorem ipsum dolorem sit amet&lt;/div&gt;';
  
              if(have_posts()) :
              while (have_posts()) : the_post();
                  $pdf_output .= '&lt;div class=&quot;post&quot;&gt;
                  &lt;h2&gt;' . $pageTitle . '&lt;/h2&gt;';
  
                  $pdf_output .= '&lt;div class=&quot;entry&quot;&gt;POST: ' .    wpautop($post-&gt;post_content, true) . '&lt;/div&gt;';
                  $pdf_output .= '&lt;/div&gt; &lt;!-- post --&gt;';
              endwhile;
  
          else :
              $pdf_output .= '&lt;h2 class=&quot;center&quot;&gt;Not Found&lt;/h2&gt;
                  &lt;p class=&quot;center&quot;&gt;Sorry, but you are looking for something that isn\'t here.&lt;/p&gt;';
          endif;
  
          $pdf_output .= '&lt;/div&gt; &lt;!--content--&gt;';
  
  
  
  $pdf_output .= '
          &lt;/body&gt;
          &lt;/html&gt;';
  </code></pre>
  <p>Everything the styles.css says is completely ignored as if the file wasn't even loaded. Interestingly enough, if I append</p>
  <pre><code>     echo '&lt;pre&gt;&lt;div id=&quot;output&quot;&gt;'.$pdf_output.'&lt;/div&gt;&lt;/pre&gt;';
       exit;
  </code></pre>
  <p>to the very end I get an HTML page and everything works just fine. Where exactly is my error here? I guess it's some kind of option in the mPDF settings.</p>