How to make blocks fill the container in several columns using css?

Question

css

codepen.io/anon/pen/ZQLKYm
here, only the first two blocks have a blue background. How to fix?
need :
1 4
2 5
3
flexbox is fine, but, as I did not expect, it does not expand the container. Leaves by the size of the first block or something like that. Weird.
What are the ways to make dynamic filling in a column?

Answer 1

Yes.. Only js crutch comes to mind..
codepen.io/anon/pen/dGNZGV - there's jQuery for a shorter entry