As of version 4.0.0 we changed the way we store the config of the (GridLayoutWebPartConfig). We recommend that you configure the layout of your pages in the User Interface. The hero widget) still uses the previous layout.
The layout defines columns and rows. We determine the amount of columns based on the screen width. There is a maximum of four columns and a minimum of one. In the User Interface you can configure the position and size of the widgets for every amount of global columns.