Defines the position of auto-generated grid items.
default
grid-auto-flow: row;
In this two-columns setup, the second grid item is two-columns wide, the third item is four-rows tall.
The other grid items are placed on additional rows.
grid-auto-flow: column;
The other grid items are placed on additional columns.
grid-auto-flow: dense;
The dense algorithm tries to place all other grid items in order to fill all the "holes" in the grid.