Is it possible and how to capture the height of the parent block?

Question

css

Is it even possible and how to automatically capture the entire height of the parent block?
I've attached a screenshot showing the design.

<div class="container">
<div class="child">11</div>
</div>

The entire width is captured (shown by the red highlight), but the height is not.
We need to capture the height of the container block to the child block.

Answer 1

What height:100%;'s not to like?
https://jsfiddle.net/mzpc5th7/