[asp.net] how to display none through code behind

I have tried this

login_div.Style("display") = "none";

But it's not working.how can I set the display of the div to none through code behind, in aspx I have a div:

<div id="login_div" runat="server">

try this

<div id="login_div" runat="server">

and on the code behind.

login_div.Style.Add("display", "none");

Since this is a login div, shouldn't the default be to NOT display it. I am going to go ahead and assume then you want to display it then via javascript.

<div id="login" style="display:none;">Content</div>

Then using jQuery:

<script type="javascript">$('#login').show();</script>

Another method you might consider is something like this:

<div id="login" style="display:<%=SetDisplay() %>">Content</div>

And the SetDisplay() method output "none" or "block"

if(displayit){
  login_div.Style["display"]="inline"; //the default display mode
}else{
  login_div.Style["display"]="none";
}

Adding this code into Page_Load should work. (if doing it at Page_Init you'll have to contend with viewstate changing what you put in it)

Try if this works:

Panel2.Style.Add("display", "none");