100 % height of a child element is not working, if parent element is set to flexbox and grow if possible

Hi there,

I have a problem: If the parent element is set to vertical flexbox and grow if possible, why 100 % height is not working on the child element?

I guess it is a very simple question and hopefully solution, too! But it is a huge problem for my layout designs.

At the page the child element is green. So the blue area should be green if 100% height would work.

Many thanks for your help!

Read only link: Webflow - marcs-problem
preview link: https://marcs-problem.webflow.io/

Anyone an idea? Or is this simpy not possible?

Tried a bit and got it! The parent element also needs to be a flex element and the child element should also have grow if possible.