C# code behind for Button Click Event, ASP.NET

You could probably get away with adding the runat="server" attribute to your buttons but I've never tried it and frankly, using proper web controls would be the best way to go.

Replacing them shouldn't change the look and feel of the page at all. Just add CssClass="xxx" to apply the css if there is any, otherwise they render to standard html elements anyway.

Your markup should look something like this:

<asp:Button runat="server" id="btnLogin" Text="Log In" OnClick="btnLogin_Click" />

The matching event handler in your code would look like this:

protected void btnLogin_Click(object sender, EventArgs e)
{
    // Here's where you do stuff.
}

you need to replace the

onclick="btnLogin_Click();"

with

onclick="btnLogin_Click"

because the onClick property of asp.net buttons need to contain the name of the function it calls in the aspx.cs file and not the actual call.

<button type="submit" runat="server" id="btnLogin"  onserverClick="btnLogin_Click1">login </button> 

just replace the onClick with onserverClick