title: How can I create a div which resizes with a window?
body: <p>I would like to create a <code>div</code> using <code>css</code> that resizes with the window. </p>
  
  <pre><code>Example:
     #container
      {
        margin: 3em;
      }
     #header {
       height: 100px;
     }
     #main {
  
     }
     #footer {
      height: 100px;
      bottom: 0px;
     }
  
     container
        header
        main
        footer
  </code></pre>
  
  <p>So when I resize the window, I want <code>main</code> to resize with the window while <code>header</code> and <code>footer</code> staty 100px;</p>
  
  <p>Is there a way to do it using CSS or I will have to use Javascript?   </p>