How to resolve Twitter share button: The allowtransparency attribute on the iframe element is obsolete. Use CSS instead.

Hello,

When validating the site http://feestdagen2013.nl I get the following error:
Error Line 17, Column 5889: The allowtransparency attribute on the iframe
element is obsolete. Use CSS instead.

When looking at the issue I see this is generated from the Twitter button
with the following code:
<a href="http://twitter.com/share" class="twitter-share-button" data-url="
http://feestdagen2013.nl" data-text="Alle feestdagen in 2013!"
data-count="horizontal">Tweet</a><script type="text/javascript" src="
http://platform.twitter.com/widgets.js"></script>

This is the code from a default Twitter share button.
Is there anyway I can resolve the issue within the code?

Any comment would be appreciated.

Sam