I have a small example of a nested flexbox setup: http://jsfiddle.net/ThomasSpiessens/MUrPj/12/
In this example the following applies:
I've found a solution without removing the extra-div.
You need to make boxContent relative positioned and its containing box absolute.
With attaching an extra css class to the inner div:
and following css:
.boxContent {
...
position: relative;
}
.innerBox{
position: absolute;
top: 0px;
bottom: 0px;
}
here's the updated jsfiddle: http://jsfiddle.net/MUrPj/223/
This question is pretty old, but this might be helpful for future visitors