Remove unneeded style attribute on Done button

Examples/CTATComboBox.html

@@ -67,7 +67,7 @@ function ctatOnload() {
       <div id="HintWindow" class="CTATHintWindow"></div>
       <div style="float:right;">
 	<div id="hint-button" class="CTATHintButton"></div>
-	<div id="done" class="CTATDoneButton" style="margin:auto;"></div>
+	<div id="done" class="CTATDoneButton"></div>
       </div>
     </div>
   </div>