Question: So i have `.cont` that's centered in using position absolute and is height 80% of body. 

Inside it there are two divs. One is fixed height. And other one needs to expand to rest of parent, `.cont`.

So How do i make it expand to parent.

One other requirement is that content in both of these needs to be vertically and horizontally centered. 

```
body
   .cont
      .top
      .fillRest

```

Here is jsfiddle: <http://jsfiddle.net/24jocwu5/>

1. make .fillRest Expand to rest of .cont.
2. vertically and Horizontally center h1 headings in both divs.

Don't Use calc()

can use display table, flow, position, and other tricks. 

![enter image description here](https://i.stack.imgur.com/k68V6.png)

Answer: 
You can use flexbox for this

```
.cont {
  display: flex;
  flex-direction: column;
}

.cont > div {
  display: flex;
}

.fillRest {
  flex: 1;
}

```

[**Working Fiddle**](http://jsfiddle.net/z24x0rvo/)
This is what you want? 
Only position fixed and right and left 0

<http://jsfiddle.net/pabliiitoo/24jocwu5/1/>

```
.fillRest {
    position: fixed;
    left: 0;
    right: 0;
    background-color: red;
    min-height: 80px;
}

```