<!DOCTYPE html>
<!--
 | Simple linear gradient from one corner to the other.
 -->
<html>
<head>
  <style>
    div {
      background: linear-gradient(to top right, red, white, blue);
      width: 200px;
      height: 200px;
    }
  </style>
</head>
<body>
  <div></div>
</body>
</html>