[AccessD] Access 2007 Form Colors question

In the Time and Billing sample app included with Access 2007, the Project
Details form has a header that fades from a darker blue on the sides to a
lighter blue in the middle. I've hunted through the form's properties and
code and cannot find how this is achieved. I like the look and would like to
use it in my own app. Can anyone help?

TIA,
Arthur