<!DOCTYPE html>

<html lang="en">
<head>
  <style type="text/css" media="screen">

    .container {
      width: 400px;
      height: 100px;
      border: 1px solid black;
      font-size: 50px;
      -webkit-column-count: 2;
      column-count: 2;
      column-fill: auto;
    }
  </style>
</head>
<body">
  
  <div class="container">
    &nbsp;<br>
    <span id="a">XXXXXX</span>
  </div>
</body>
</html>