title: How to prevent black background when saving a div to png
body: <p>I´m using HTML2canvas, filesaver.js and canvas2blob.js to achieve an in-browser save-dialogue. The on-the-fly canvas-creation and saving works fine except the image background is black.</p>
  
  <p>The problem is the base64-encoded image of the div with id="drop1" (the user drags and drops an image from his desktop to the html and then that image is put as background as base64).</p>
  
  <p>How can I achieve a visible output in the png file?</p>
  
  <p>my JS:</p>
  
  <pre><code>// save img magic
  // html2canvas.js linked with filesaver.js and canvas2blob.js for compatibility polyfilling
  $('#1stSave').click(function() {
      var html2obj = html2canvas($('#drop1'));
      var queue  = html2obj.parse();
      var canvas = html2obj.render(queue);
      canvas.toBlob(function(blob) {
          saveAs(blob, "teaser-384x168px.png");
      });
  });
  </code></pre>
  
  <p>Thanks so much in advance :)</p>