changing background-color after button click

Hi i have some buttons in my detailsview like this <div id="xx" runat="server"> <asp:Label ID="lblMessage" Visible="false" runat="server" Text="Label"></asp:Label> <asp:LinkButton ID="lbProgramm" OnClick="btn_click" runat="server">Programm</asp:LinkButton> <asp:LinkButton ID="lbOrt" OnClick="btn_click" runat="server">Veranstaltungsort/Kosten</asp:LinkButton> <asp:LinkButton ID="lbLeitung" OnClick="btn_click" runat="server">Leitung</asp:LinkButton> <asp:LinkButton ID="lbMerken" OnClick="btn_click" runat="server">Thema merken</asp:LinkButton> <asp:LinkButton ID="lbAnmeldung" OnClick="btn_click ...