jsp achieve table form with scroll bar

<!--div比table的width要小滚动条才会显示-->
            <div class="box-vertical" style="width: 400px; max-height: 240px; overflow:auto;">
            <table id="tab_1" style="width: 400px;" cellpadding="0"
            cellspacing="1" class="formtable">
            <tr>
                <th align="center">序号</th>
                <th align="center"<>TH</Billing date>
                th align="center">记账汇率</th>
            </tr>
             <tbody id="tbd">
            </tbody> 
            </table>
            </div>