title: CSS Div fill remaining height
body: <p>Please see my <a href="https://jsfiddle.net/ugjfwbg4/" rel="noreferrer">jsfiddle</a></p>
  
  <p>I want the green middle <code>div</code> to fill the remaining space of the wrapper <code>div</code> no matter how much content it has.</p>
  
  <p>If it matters I'm including bootstrap too.</p>