Modal Popup Extender panel height width

I have a ajax asp.net modalpopupextender, I wont when I desplay popup, the popup cover all the browser window.

The popup display a panel one is inside the form not other container.

My .aspx code is: < asp:Panel ID="OptionPanel" runat="server" CssClass="mp"

Style="display: block; width:100%; height:100开发者_如何学运维%">

But don't work!!!

Any ideas????

ModalPopupExtender's main Panel should not have block display style, it must be hidden:

The ModalPopupExtender that this popup is attached to has a hidden TargetControl.

E.g. Style="display: hidden;"

The size of Panel (div) can be resized with JS, for example.