Hi Gary,

WebGroupBox does not provide options to customize appearance of title (legend element).

Application may use static css classes for that and access legend by selector for ClientID of group-box. Below is example (codes in head with assumption that form has WebGroupBox1 control):

<style type="text/css">
#WebGroupBox1 legend
{
  background: cyan;
  border: 1px solid red;
  font-size: 20px;
}
</style>