flex example

HTML

<div class="box">
  <div class="row header">
    <p><b>header</b>
      <br />
      <br />(sized to content)</p>
  </div>
  <div class="row content">
    <div id="col1" class="col">col 1</div>
    <div id="col2" class="col">
      <p>col 2</p>
      <p>col 2</p>
      <p>col 2</p>
      <p>col 2</p>
      <p>col 2</p>
      <p>col 2</p>
      <p>col 2</p>
      <p>col 2</p>
    </div>
  </div>  
  <div class="row footer">
    <p><b>footer</b> (fixed height)</p>
  </div>
</div>

CSS

html,
body {
  height: 100%;
  margin: 0
}

.box {
  display: flex;
  flex-flow: column;
  height: 100%;
}

.box .row.header {
  flex: 0 1 auto;
}

.box .row.content {
  display: flex;
  flex-flow: row;
  flex: 1 1 auto;
}

#col1 { 
  flex: 0 1 50px;
  background: lightgreen;
}

#col2 { 
  flex: 1 1 auto;
  overflow: auto;
  background: lightblue;
}

.box .row.footer {
  flex: 0 1 40px;
}