Problem with positioning of charts in superset dashboard

I want to put some charts on Superset dashboard. The layout I want is like this:

 ____________________
|          |         |
|          |    B    |
|    A     |_________|
|          |         |
|          |    C    |
|__________|_________|

A is a chart with some main info and B and C are details of it. The problem is if I put B as it is then C cannot be put below B and will form a completely new row. I tried to achieve this form with an empty row or column or separator and no luck yet.

Try following these steps and see if it works:

1. Add an empty row
2. Add two empty columns in it
3. Add two empty rows on the right column
4. Add charts into desired cells.
5. Adjust width and height.