This theme includes one of the effects from Codrops you can demo here and installed in a fresh copy of the Genesis Sample child theme by StudioPress.
Simply add any content you like to the Layout Widget area added to this theme and your content will display when the overlay button is clicked.
In the following sample, the button has been named Download eBook and added to the genesis nav menu as seen in the following image:
The above example shows the Genesis eNews widget added to the Layout Widget area with some basic styling. Here’s the widget settings:
Add any widget you want displayed when the button is clicked or change the button to an icon. You can easily change the position of the button and style the overlay background and widget using basic CSS.
Here’s the theme you can download and use “as is” or take the code out and add it to another genesis child theme.