<!DOCTYPE html>
<html>
<head>
  <style type="text/css">
  div{
      height: 100px;
      width: 100px;
      background-color

urple;
      }
  </style>
  <script>
   addEventListener('DOMContentLoaded',
    function() {
   const elem = document.querySelector('div'),
   size = [innerWidth - 100, innerHeight - 100],
   random = a => a * Math.random()|0,
   timer = () => {
       const [left, top] = size.map(random);
     elem.style.transform = `translate(${left}px, ${top}px`;
   };
elem.addEventListener('click',timer)
     });
  </script>
</head>
<body bgcolor = black;>
<div></div>
</body>
</html>