求inline-block水平居中旋钮的css完美版 _HTML/CSS

求inline-block水平居中按钮的css完美版
求inline-block水平居中按钮的css完美版
请问我下面的代码是不是最完美了？无论在什么浏览器都会水平居中？

HTML code


<!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>
<title>button middle</title>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
</head>
<body>
    <style type="text/css">
        *{margin:0;padding:0}
        .mgl20{margin-left:20px;}
        .btns_line{
            background-color:tan;
            margin:20px;
            padding:30px;
            border:1px solid gray;
            text-align:center;
            word-spacing:-6px;
        }
        .btn {
            display:inline-block;
            padding-left: 15px;
            background-position: left top;
            text-align: center;
            background-repeat: no-repeat;
            color: #FFFFFF;
            font-size: 20px;
            font-weight: bold;
            cursor: pointer;
            word-spacing: 0;
            background-image:url(btn_gray_left.png);
            width:150px;
            height:34px;
            line-height:34px;
        }
        .btn span {
            padding-right: 15px;
            display: block;
            height: 100%;
            background-position: right top;
            background-repeat: no-repeat;
            width: auto;
            cursor: pointer;
            background-image:url(btn_gray_right.png);
        }
    </style>
    <div class="btns_line">
        <a href="#" class="btn"><span>hello world</span></a>
        <a href="#" class="btn mgl20"><span>hello world</span></a>
    </div>
</body>
</html>

------解决方案--------------------
呵呵。。这个我也早有做过。。学习了
按钮分页距中display:inline-block完美解决
http://www.ok22.org/art_detail.aspx?id=374