title: Why isn't my CSS style changing the attribute height here?
body: <p>If I set width of the "div" element to % it works fine, but if I set the height to a % I get nothing. Only if I specify the height in px or em or something does it work:</p>
  
  <pre><code>&lt;!DOCTYPE html&gt;
  &lt;html&gt;
    &lt;head&gt;
      &lt;meta charset="utf-8"&gt;
    &lt;/head&gt;
      &lt;style&gt;
          div {
              background-color: aqua;
              height: 25%;
              width: 25%;
               float: left; 
              }
      &lt;/style&gt;
  
  &lt;body&gt;
     &lt;div&gt;&lt;/div&gt;
  &lt;/body&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>This is confusing me. Thanks.</p>