What did he do in this video? from 2:30-2:33?

[AestheticDesign.]

I'm trying to figure out what he did from 2:30-2:33

How did he make the the white rectangle show up like it's on top of the purple?

 

Thanks for the help.

 

[R C-R]

The white roof shape was duplicated via copy & paste, then the lower one was colored purple & moved down slightly to create the shadow.

[AestheticDesign.]

8 minutes ago, R C-R said:

The white roof shape was duplicated via copy & paste, then the lower one was colored purple & moved down slightly to create the shadow.

About the "moved down slightly" part.

 

Whenever i try to (even slightly) move the rectangle. It starts to misalign with the triangle. Is there any specific method to how he "moved down slighty?" 

 

Or just literally moved down slightly? 

[R C-R]

One way is to hold down the Shift key to constrain the movement to horizontal or vertical. You can also use the up/down cursor keys to move an item vertically by small steps. Holding down the Alt/Option key after you start a drag temporarily disables snapping, or you can turn off snapping in the Main Toolbar by clicking on the Magnet button.