不定宽度居中

重点：不要浮动
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>不确定内容宽度</title>
</head>
<style>
    .box{ width:1000px; background:red; text-align:center;}
    .content .pic{ display:inline-block;}
    .content{ margin:0 auto; width:auto;}
</style>
<body>
    <div class="box">
        <div class="content">
            <div class="pic"><img src="http://www.baidu.com/img/bdlogo.gif"/></div>         
           <span>文本很长很长文本长很长</span>
        </div>
    </div>
</body>
</html>