dijit.form.DateTextBox - setting a class on the calendar popup?

http://stackoverflow.com/questions/11342335/dijit-form-datetextbox-setting-a-class-on-the-calendar-popup

HTML

<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/dojo/1.7.2/dijit/themes/claro/claro.css">
<div id="cal1" jsId="cal1" data-dojo-type="dijit.form.TimeTextBox"></div>

CSS

.claro .dijitCalendarPopup .dijitCalendar.myCal {
 background-color: black;   
}

JavaScript

require(["dojo/aspect", "dojo/parser", "dijit/form/DateTextBox"]);

dojo.ready(function() {
    
    require(["dojo/aspect"], function(aspect) {
        var cal = dijit.byId('cal1');
        aspect.after(cal, "openDropDown", function(deferred){
            console.dir(cal.dropDown);
            dojo.addClass(cal.dropDown.domNode, 'myCal');
        });
    });
    
});