How to make such transitions between sections?

Question

css

Is there such a thing as how to do it?
According to the layout further and in the opposite direction, tobish and convex and "in total"

Answer 1

There are 2 sections - upper and lower. The top one is a png image, fixed on the bottom edge of the top block on top of all the content, or you can play around with css transformations.

Answer 2

Solved via elementary border-radius