hi, try editing this file:

hcl/templates/G/css/chat.css

aprox on line 83 modify this code:

#content {
    padding-top: 15px;
    padding-left: 10px;
    padding-right: 10px;
    padding-bottom: 15px;
   background-image: url(../images/bg/popup_page.jpg);
   background-repeat: repeat-x;
}