title: Scrolling a flexbox with overflowing content
body: <p><img src="https://i.stack.imgur.com/LzsBQ.png" alt="enter image description here"></p>
  
  <p><a href="http://codepen.io/JosephSilber/pen/qGebw" rel="noreferrer">Here's the code</a> I'm using to achieve the above layout:</p>
  
  <p><div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
  <div class="snippet-code">
  <pre class="snippet-code-css lang-css prettyprint-override"><code>.header {
    height: 50px;
  }
  
  .body {
    position: absolute;
    top: 50px;
    right: 0;
    bottom: 0;
    left: 0;
    display: flex;
  }
  
  .sidebar {
    width: 140px;
  }
  
  .main {
    flex: 1;
    display: flex;
    flex-direction: column;
  }
  
  .content {
    flex: 1;
    display: flex;
  }
  
  .column {
    padding: 20px;
    border-right: 1px solid #999;
  }</code></pre>
  <pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;div class="header"&gt;Main header&lt;/div&gt;
  &lt;div class="body"&gt;
    &lt;div class="sidebar"&gt;Sidebar&lt;/div&gt;
  
    &lt;div class="main"&gt;
      &lt;div class="page-header"&gt;Page Header. Content columns are below.&lt;/div&gt;
      &lt;div class="content"&gt;
        &lt;div class="column"&gt;Column 1&lt;/div&gt;
        &lt;div class="column"&gt;Column 1&lt;/div&gt;
        &lt;div class="column"&gt;Column 1&lt;/div&gt;
      &lt;/div&gt;
    &lt;/div&gt;
  &lt;/div&gt;</code></pre>
  </div>
  </div>
  </p>
  
  <p>I omitted the code used for styling. You can see all of it in <a href="http://codepen.io/JosephSilber/pen/qGebw" rel="noreferrer">the pen</a>.</p>
  
  <hr>
  
  <p>The above works, but when the <code>content</code> area's content overflows, it makes the whole page scroll. I only want the content area itself to scroll, so <a href="http://codepen.io/JosephSilber/pen/buwGD" rel="noreferrer">I added <code>overflow: auto</code> to the <code>content</code> div</a>.</p>
  
  <p>The problem with this now is that the columns themselves don't extend beyond their parents height, so the borders are cut off there too.</p>
  
  <p><a href="http://codepen.io/JosephSilber/pen/buwGD" rel="noreferrer">Here's the pen showing the scrolling issue</a>.</p>
  
  <p><strong>How can I set the <code>content</code> area to scroll independently, while still having its children extend beyond the <code>content</code> box's height?</strong></p>