overlaySwatch
Specifies the default jQuery Mobile theme swatch, or color scheme, to apply to the overlay layer for the dialog-based custom select menus and the outer border of the smaller custom menus.
Default value
Default - Uses the weblet's default swatch or inherits the swatch from the container.
Valid values
Any single letter from a-z. The shipped them only contains swatches a-b. See the jQuery Mobile documentation on themes for details of how to create your own themes.