frame居中显示？

<div id="shoulderBar">

  <dl>

    <dd id="expo">2010年上海世博会开幕第 <span>

	<script language="javascript">

	var expo_start_date = new Date(2010, 04, 01); // 2010-5-1

	var today = new Date();

	var t = today.getTime() - expo_start_date.getTime();

	var d =  Math.floor(t / (1000 * 60 * 60 * 24)) + 1;

	document.write(d);

	</script>

	</span> 天</dd>

	<%

		Date d = new Date();

        SimpleDateFormat sdf = new SimpleDateFormat("yyyy年MM月dd日");

        String date = sdf.format(d);		

		Calendar now = Calendar.getInstance();

		//星期数，从星期天开始到星期六为0-7 

		now.setTime(d);

		now.get(Calendar.DAY_OF_WEEK);

		int week=now.get(Calendar.DAY_OF_WEEK);

		String   strWeek= " "; 

            switch(week){ 

                            case   1:   strWeek= "星期日 "; 

                                            break; 

                            case   2:   strWeek= "星期一 "; 

                                            break; 

                            case   3:   strWeek= "星期二 "; 

                                            break; 

                            case   4:   strWeek= "星期三 "; 

                                            break; 

                            case   5:   strWeek= "星期四 "; 

                                            break; 

                            case   6:   strWeek= "星期五 "; 

                                            break; 

                            case   7:   strWeek= "星期六 "; 

                                            break; 

                            default:   strWeek= " "; 

            } 

	%>

	<dd><%=date%></dd>

	<dd><%=strWeek%></dd>



    <dd id="weather"><span>

	<iframe src="http://m.weather.com.cn/m/pn2/weather.htm?id=101020100T " width="180" height="40" marginwidth="0" marginheight="0" hspace="0" vspace="8" frameborder="0" allowtransparency="true" scrolling="no"></iframe></span></dd>

  </dl>

  <div id="search">

    <ul>

      <li><span>全文检索</span></li>

      <li>

        <input name="textfield" type="text" class="search" id="textfield" value="请输入关键字" />

      </li>

      <li>

        <input name="button" type="submit" class="btn" id="button" value="" />

      </li>

    </ul>

  </div>

</div>