title: middle div take up remaining space?
body: <p>I have three <code>div</code>s,</p>
  
  <pre><code>divl : 7px width
  divr: 7px width
  divm: unknown
  </code></pre>
  
  <p>What I want to do is:</p>
  
  <ul>
  <li>Have <code>divl</code> at the very left of the parent <code>div</code>,</li>
  <li><code>divr</code> at the very right of the parent <code>div</code>.</li>
  <li><code>divm</code> in between those two <code>div</code>s and span the remaining space.</li>
  </ul>
  
  <p>How can I do this?</p>