CSS控制GridView固定表頭

CSS代碼

<style type="text/css"> 
    .Freezing 
   {}{     
       position:relative ; 
       table-layout:fixed;
       top:expression(this.offsetParent.scrollTop);   
       z-index: 10;
   } 

.Freezing th{}{text-overflow:ellipsis;overflow:hidden;white-space: nowrap;padding:2px;}
</style>

調用代碼     <div style="overflow-y: scroll; height: 200px; width: 300px">    <!--設定Div帶捲軸-->
            <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" CellPadding="3"
                BackColor="White" BorderColor="#CCCCCC" BorderStyle="None" BorderWidth="1px"
                Font-Size="12px" DataKeyNames="ProductID" DataSourceID="SqlDataSource1" AllowSorting="True">
                <FooterStyle BackColor="White" ForeColor="#000066" />
                <Columns>
                    <asp:CommandField ShowSelectButton="True" />
                    <asp:BoundField DataField="ProductID" HeaderText="ProductID" ReadOnly="True" SortExpression="ProductID" />
                    <asp:BoundField DataField="SupplierID" HeaderText="SupplierID" SortExpression="SupplierID" />
                    <asp:BoundField DataField="ProductName" HeaderText="ProductName" SortExpression="ProductName" />
                    <asp:BoundField DataField="CategoryID" HeaderText="CategoryID" SortExpression="CategoryID" />
                </Columns>
                <RowStyle ForeColor="#000066" />
                <SelectedRowStyle BackColor="#669999" Font-Bold="True" ForeColor="White" />
                <PagerStyle BackColor="White" ForeColor="#000066" HorizontalAlign="Left" CssClass="ms-formlabel DataGridFixedHeader" />
                <HeaderStyle BackColor="#006699" Font-Bold="True" ForeColor="White" CssClass="Freezing" /></asp:GridView>
<!--調用樣式固定表頭-->

        </div>