How to set height and width of aspxpopupcontrol dynamically?

Hello,
       I am having a requirement where I have to increase the popupcontrol based on the content. Baasically I am loading a user control dynamically to aspxpopupcontrol. The user control has callbackpanel where the content is rendered based on the radio button which is also part of user control. The need is here to dynamically increase the widith and height of aspxpopupcontrol. I am able to resize and it works in all desktop to specified size based on selected radio button. Below I ahve given the piece of js code that does this.
function SetPopupSize(sender, height, width) {
    var popupWidth, popupHeight;
// popupWidth = window.parent.document.documentElement.clientWidth * (width / 100);
// popupHeight = window.parent.document.documentElement.clientHeight * (height / 100);
popupWidth = screen.width * (width / 100);
    popupHeight = screen.height * (height / 100);
    sender.SetSize(popupWidth, popupHeight);
    sender.UpdatePosition();
I have commented two lines which is also working. But it works different in laptop and small screens. so tired the screen.height and width to set the size. It renderes fine in all desktop screen. But I am getting vertical scroll bar mostly and sometimes getting horizontal scroll bar in laptop screens. What I have to do to make it consistent based on screen resolution. Please let me know regardign this.
Regards,
Elango
}