Hi WangNi wang,
I checked further and tried to set everything White in Style. But even in this case the cell boundaries showed in grid.
So, as per my understanding it is not possible to hide the boundaries of the cells in Grid.
If you want to hide the cell boundaries; then use Repeater Widget.
Your requirement can be achieved easily via Repeater Widget.
For details on how to use the Repeater Widget check following Video: https://www.youtube.com/watch?v=zXrKq1tvntU
Do let me know if you still have any queries.