title: Height equal to dynamic width (CSS fluid layout)
body: <p>Is it possible to set same height as width (ratio 1:1)?</p>
  
  <p><strong>Example</strong></p>
  
  <pre><code>+----------+
  | body     |
  | 1:3      |
  |          |
  | +------+ |
  | | div  | |
  | | 1:1  | |
  | +------+ |
  |          |
  |          |
  |          |
  |          |
  |          |
  +----------+
  </code></pre>
  
  <p><strong>CSS</strong></p>
  
  <pre><code>div {
    width: 80%;
    height: same-as-width
  }
  </code></pre>