Buttons fade upon submit after validation

I have 2 buttons that do validation before sending I would like to make them inactive when the validation is done. here is my code I will appreciate if anyone can help with my current code, since it is the only way I could validate my form.
<asp:Button ID="Button2" runat="server" Text="Save " OnClientClick="return Page_ClientValidate('gp1')" BackColor="#009933" Font-Bold="True" ForeColor="White" PostBackUrl="~/Save_thankyou.aspx" style="text-align: center" /> <asp:Button ID="Button1" runat="server" Text="Submit " OnClientClick="return validate() " BackColor="#3366FF" Font-Bold="True" ForeColor="White" PostBackUrl="~/submit_thankyou.aspx" style="tex ...