how to fix header in gridview on scrolling in asp.net c#

fix gridview header on scroll
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Add the following style in your code and assign the grid view or datagrid header style css.

.fixedHeader
{
font-weight:bold;
position:absolute;
background-color: #006699;
color: #ffffff;
height: 25px;
top: expression(Sys.UI.DomElement.getBounds(document.getElementById("panelContainer")).y-25);
}
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<asp:Panel ID="panelContainer" runat="server" Height="300px" Width="100%"  ScrollBars="Vertical">
<asp:GridView ID="gvScrollableExample" runat="server">
<HeaderStyle CssClass="fixedHeader " />
</asp:GridView>
</asp:Panel>