I make div clickable using linkbutton inside updatepanel..but when I click div whole page

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C#

ASP.NET

<<pre lang="HTML">asp:UpdatePanel ID="UpdatePanel2" UpdateMode="Conditional" ChildrenAsTriggers="false" runat="server">
<Triggers>
<asp:AsyncPostBackTrigger ControlID="rptEmployer" />
<asp:AsyncPostBackTrigger ControlID="btn_first" />
<asp:AsyncPostBackTrigger ControlID="btn_previous" />
<asp:AsyncPostBackTrigger ControlID="btn_next" />
<asp:AsyncPostBackTrigger ControlID="btn_last" />
<asp:AsyncPostBackTrigger ControlID="drp_count" />
<asp:AsyncPostBackTrigger ControlID="txtsearch" />
</Triggers>
<ContentTemplate>
<div class="grid_container">
<asp:TextBox ID="txtsearch" CssClass="srch" AutoPostBack="true" runat="server" placeholder="Search Employer" OnTextChanged="txtsearch_TextChanged"></asp:TextBox>
<asp:Repeater ID="rptEmployer" OnItemCommand="rptEmployer_ItemCommand" runat="server">
<ItemTemplate>
<asp:LinkButton ID="lb_emp_list" Style="text-decoration: none;" CommandName="Edit" runat="server">
<div class="employer_list">
<div class="serial">
<%# Eval("RowNumber") %>
</div>
<div class="detail">
<b>Tax Id :</b> <%# Eval("EmployerTaxId") %><br />
<%# Eval("name") %><br />

</div>
<asp:HiddenField ID="hdn_EmpTax_Id" Value='<%# Eval("EmployerTaxId") %>' runat="server" />
<asp:HiddenField ID="hdn_CompanyTax_Id" Value='<%# Eval("CompanyTaxID") %>' runat="server" />
</div>
</asp:LinkButton>
</ItemTemplate>
</asp:Repeater>
<table>
<tr>
<td>
<asp:Button ID="btn_first" CssClass="btn_nav" runat="server" Text="<<" OnClick="btn_first_Click" />
<asp:Button ID="btn_previous" CssClass="btn_nav" runat="server" Text="<" OnClick="btn_previous_Click" />
<asp:Label ID="lbl_pagenum" runat="server" Text=""></asp:Label>
<asp:Button ID="btn_next" CssClass="btn_nav" runat="server" Text=">" OnClick="btn_next_Click" />
<asp:Button ID="btn_last" CssClass="btn_nav" runat="server" Text=">>" OnClick="btn_last_Click" />
<asp:DropDownList ID="drp_count" runat="server" AutoPostBack="True" OnSelectedIndexChanged="drp_count_SelectedIndexChanged">
<asp:ListItem Value="10">10</asp:ListItem>
<asp:ListItem Value="20">20</asp:ListItem>
<asp:ListItem Value="50">50</asp:ListItem>
<asp:ListItem Value="100">100</asp:ListItem>
</asp:DropDownList><br />
<asp:Label ID="lbl_result" runat="server" Text=""></asp:Label>
<asp:HiddenField ID="hid_rowcount" runat="server" />
<asp:HiddenField ID="hdn_companytax_id" runat="server" />
</td>
</tr>
</table>
</div>
</ContentTemplate>
</asp:UpdatePanel
>

What I have tried:

<asp:UpdatePanel ID="UpdatePanel2" UpdateMode="Conditional" ChildrenAsTriggers="false" runat="server">
<triggers> <asp:AsyncPostBackTrigger ControlID="rptEmployer" />
<asp:AsyncPostBackTrigger ControlID="btn_first" />
<asp:AsyncPostBackTrigger ControlID="btn_previous" />
<asp:AsyncPostBackTrigger ControlID="btn_next" />
<asp:AsyncPostBackTrigger ControlID="btn_last" />
<asp:AsyncPostBackTrigger ControlID="drp_count" />
<asp:AsyncPostBackTrigger ControlID="txtsearch" />
<contenttemplate>