Dhtmlx popup color change

Hi ,

I need some help in applying style to the dhtmlx popup. I need to change the background color of popup to dark blue and apply border radius to the popup .
Can anyone please post some sample code to do the same. Thanks in advance.

The only available customization is to apply another skin or change the css styles of the popup:
div.dhx_popup_dhx_skyblue div.dhx_popup_area{
//required css