title: How to set height of div match its container
body: <p>I have a div which is container. This div contain 2 div tags, as below:</p>
  
  <pre><code>&lt;style type="text/css"&gt;
  #container{
      height:100%
  }
  
  #child1{
      height:35px;
  }
  
  #child2{
      overlow-y:auto;
      height: ??? /**to match remain space of container**/
  }
  &lt;/style&gt;
  
  
  &lt;div id="container"&gt;
      &lt;div id="child1"&gt;this is a child1&lt;/div&gt;
      &lt;div id="child2"&gt;this is a child2&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>How can I set child2's height to match remain space of container which is vertical scroll bar if child2's content is too much?</p>