<!DOCTYPE html>
<html>
    <head>
        <style type="text/css">
            div {
              word-spacing: 20px;
              float: left;
              border: solid;
              clear: both;
            }
        </style>
    </head>
    <body>
        <p>The lines below should be the same width.</p>
        <div>a &nbsp;b</div>
        <div>a&nbsp;&nbsp;b</div>
  </body>
</html>