<!DOCTYPE html>
<!--
 | Setting 3 different width values for a rounded corners border.
 |   https://www.w3.org/TR/css3-background/#the-border-width
 -->
<html>
<head>
  <style>
    div {
      border: solid #00FFFF;
      border-width: 80px 50px 10px;
      border-radius: 50%;
      height: 200px;
      width: 400px;
    }
  </style>
</head>
<body>
  <div></div>
</body>
</html>