title: How to make a changing color shape?
body: <p>Hey I know how to make rainbow background, it is easy </p>
  
  <pre><code>&lt;html&gt;
  &lt;center&gt;
  &lt;head&gt;
  &lt;style&gt;
  body {
      background-color: red;
      transition: background-color 5s;
  }
  &lt;/style&gt;
  &lt;/head&gt;
  &lt;body&gt;
  &lt;script type="text/javascript"&gt;
  var colors = ["red", "orange", "yellow", "green", "blue", "indigo", "violet"];
  
  var i = 1;
  
  window.setInterval(function(){
  document.body.style.backgroundColor = colors[i];
  i++;
  if (i === colors.length){
  i=0;
  }
  }, 5000);
  &lt;/script&gt;
  &lt;/body&gt;
  &lt;/center&gt;
  &lt;/html&gt;
  </code></pre>
  
  <p>But do you know how to make for example a changing color circle or other shapes using this code?
  Thanks.</p>