<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>Split panels</title>
  <script type="text/javascript" src="https://unpkg.com/split.js/dist/split.min.js"></script>
</head>
<body>
  <div>
    <div id="one">content one</div>
    <div id="two">content two</div>
    <div id="three">content three</div>
  </div>
</body>
<script type="text/javascript">
  window.onload = function() {
    Split(['#one', '#two'], {
      sizes: [25, 75],
      minSize: 200
    });
  };
</script>
</html>