Why does my flex navbar not allow height to stretch?

Question

css

How to figure out why I can't stretch to the full height of the navbar where the tests.

I tried https://jsfiddle.net/hollanditkzn/2c9L13g3/1/ It happened, but I don’t understand why she doesn’t like it.
I use yii2 and if you look in the console what gives such a large range, then this is class='wrap'
If you remove it, the footer will run, but it's not clear how to make it so that it was from header to footer

Answer 1

https://jsfiddle.net/1n6ueuhp/3/ - look, is this necessary?