How to have border for all cells in GridView ASP.Net

Check this

<asp:GridView ID="GridView1" runat="server" AutoGenerateColumns = "false" GridLines = "Both">
    <Columns>
        <asp:BoundField DataField = "Item" ItemStyle-CssClass = "Item"/>
        <asp:TemplateField>
        <ItemTemplate>
            <asp:TextBox ID="txtPrice" CssClass = "Price" runat="server" Text = '<%# Eval("Price") %>'></asp:TextBox>
        </ItemTemplate>
        </asp:TemplateField>
         <asp:TemplateField>
        <ItemTemplate>
           <asp:LinkButton  ID = "lnkSelect" runat="server" Text = "Select"></asp:LinkButton>
        </ItemTemplate>
        </asp:TemplateField>
    </Columns>
    </asp:GridView>

Demo