title: Leaflet cluster group background color does not appear in map print export
body: <p>I have a Leaflet map with a L.markerClusterGroup. It looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/JPRRV.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/JPRRV.png" alt="enter image description here"></a></p>
  
  <p>But when printing (to PDF), it looks like this:</p>
  
  <p><a href="https://i.stack.imgur.com/ZxiEN.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ZxiEN.png" alt="enter image description here"></a></p>
  
  <p>Notice the absence of background colour.</p>
  
  <p>The points are created as follow:</p>
  
  <pre><code>L.DivIcon({ html: '&lt;div&gt;&lt;span&gt;' + (childCount + tally) + '&lt;/span&gt;&lt;/div&gt;', className: 'marker-cluster' + &lt;my own css&gt;, iconSize: new L.Point(40, 40) });
  </code></pre>
  
  <p>Where "my own css" are css classes that may be either of following:</p>
  
  <pre><code>background: rgba(255, 0, 192, 0.3); !important;
  border: 1px solid #666;
  </code></pre>
  
  <p>Or</p>
  
  <pre><code>background: rgba(9, 243, 33, 0.6);!important;
  border: 1px solid #666;
  </code></pre>
  
  <p>Anyone else ever had the same issue?</p>