<!DOCTYPE html>
<html>
   <head>
       <style type='text/css'>
           #container {
           position: relative;
           }
           .abs {
               outline: solid 1px skyblue;
                position: absolute;
                left: 0;
                top: 0;
                right: 0;
            }
        </style>
        <script type='text/javascript'>
            window.onload=function(){
            var span = document.createElement('span');
            span.innerHTML = ' moooore';
            document.getElementById('container').appendChild(span);
            };
        </script>
    </head>
    <body>
        <p>When you click <button id="more">moooore</button>, the span.abs should expand with the container</p>
        <p><span id="container"><span class="abs">&nbsp;</span>Words, words, words</span>
    </body>
</html>