Center children and z-index

Question

How can I center the children horizontally in the page and stack the circles under .centered?
https://sololearn.com/compiler-playground/WEgURf0EFPaW/?ref=app

Answer 1

If I understand your question correctly, you would put the children in a div and centre that. What do you mean by stack?

Answer 2

Sorry for not being clear, how to make the elements within .centered display horizontally centered within the page?

With stack, I'm trying to arrange the circle elements to look like they're under the .centered element with Z-index property.
https://sololearn.com/compiler-playground/WnfPs6Ey5JAG/?ref=app
A little like this

Answer 3

don't nest the 3 circles in the .centered div