I am using Asp.net 4.0 GridView control to display data from database. I have applied the inbuilt theme to GridView.

    <asp:GridView ID="gv" runat="server" CellPadding="4" EmptyDataText="No records found."
    ForeColor="#333333" OnRowCommand="gv_RowCommand" Width="99%" OnPageIndexChanging="gv_PageIndexChanged"
    PageSize="50" AllowPaging="True" GridLines="None" AutoGenerateColumns="true">
    <AlternatingRowStyle BackColor="White" />
    <EditRowStyle BackColor="#7C6F57" />
    <FooterStyle BackColor="#1C5E55" Font-Bold="True" ForeColor="White" />
    <HeaderStyle CssClass="GridHeader" BackColor="#1C5E55" Font-Bold="True" ForeColor="White" HorizontalAlign="Left" />
    <PagerStyle BackColor="#666666" ForeColor="White" HorizontalAlign="Center" />
    <RowStyle BackColor="#E3EAEB" />
    <SelectedRowStyle BackColor="#C5BBAF" Font-Bold="True" ForeColor="#333333" />
    <SortedAscendingCellStyle BackColor="#F8FAFA" />
    <SortedAscendingHeaderStyle BackColor="#246B61" />
    <SortedDescendingCellStyle BackColor="#D4DFE1" />
    <SortedDescendingHeaderStyle BackColor="#15524A" /></asp:GridView>

I tried setting the CSS forcefully in my Master page

        .GridHeader { background-color:#1C5E55 !important;}

But I am still missing the background-color.

I can see the backgroundcolor applied to grid (for less-than 1 sec) while the page loading the js/css content

NOTE: I already tried clearing cache of IE, ctrl + F5, shift + reload etc.

Here is sample page of my issue.

http://vd2.weenggs.com/Items.aspx

email: [email protected]

pass: test

Thanks