If I needed to do it, I would. But I don’t.
If I had to do it, I would do the shadow with a slightly bigger arrangement with a transparent grey as background color. Then I would use the size of the main container to calculate the height and width of each component contained, that way it would be responsive to the main container size.
That would be a procedure with no more than 10 blocks. I actually learned something while thinking how to do it. Thank you for the challenge!
Then my app would depend only on my design, I would not have to worry about incompatibilities with other extensions, and I will be able to customize it any way I want.