div居中和table居中

 .searchclass 
 {
      width:960px;
      min-height:80px;
      border-right:1px solid #000;border-bottom:1px solid #000;
      margin:auto;
      
 }
  .searchclass  tr td
 {
       height:15px;
       border-left:1px solid #000;border-top:1px solid #000
 }

  <table class="searchclass">
    <tr><td><asp:label id="Label9" Width="120px" runat="server">有效截止日期:</asp:label></td><td><asp:label id="lblTillDate" Width="120px" runat="server" ForeColor="#FF8080"></asp:label></td><td colspan="2"></td></tr>
    <tr><td> Check-in：<asp:dropdownlist id="lstFADD" Width="48px" runat="server" ></asp:dropdownlist></td>
    <td><asp:dropdownlist id="lstFAMMYY" Width="85px" runat="server"></asp:dropdownlist></td>
    <td>Nights :<asp:dropdownlist id="lstNights" Width="48px" runat="server" ></asp:dropdownlist></td>
    <td><asp:Button ID="btnsearch" runat="server" Text="查询" /><asp:Button ID="btnExcel" runat="server" Text="Export to Excel" /></td>
    </tr>
     <tr>
     <td colspan="2">开始时间：
     <asp:dropdownlist id="lstFADDFnestart" Width="48px" runat="server" ></asp:dropdownlist> &nbsp;&nbsp;
     <asp:dropdownlist id="lstFAMMYYFnestart" Width="85px" runat="server"></asp:dropdownlist>
     </td>
      <td colspan="2">截止时间：
      <asp:dropdownlist id="lstFADDFneend" Width="48px" runat="server" ></asp:dropdownlist> &nbsp;&nbsp;
     <asp:dropdownlist id="lstFAMMYYFneend" Width="85px" runat="server"></asp:dropdownlist>
      </td>
     </tr>
     <tr><td colspan="4"><asp:Button ID="btnsaveFne" runat="server"  Text="Save"/></td></tr>
     </table>