Its referred to as the dialog box
Code:
.DialogBox {
BACKGROUND-COLOR: #ffffff;
}
.DialogBorder {
BACKGROUND-COLOR: #FF8600;
}
.DialogTitle {
COLOR: #000000; FONT-WEIGHT: bold; FONT-SIZE: 12px;
}
You will have to manually recolor the graphic though that makes the tab piece, you can't just change the CSS for that.