function GetClientWidth() {
    return document.documentElement.clientWidth ? document.documentElement.clientWidth : document.body.clientWidth;
}

function GetClientHeight() {
    return document.documentElement.clientHeight ? document.documentElement.clientHeight : document.body.clientHeight;
}

function OnLoadIntro() {
    ResizeIntro();
}

function OnResizeIntro() {
    ResizeIntro();
}

var imageWidth = 900;
var imageHeight = 700;

function ResizeIntro() {
    var f = document.getElementById("intro");
    if (f != null) {
        var w = GetClientWidth();
        var h = GetClientHeight();
        var x = (w-imageWidth)/2;
        var y = (h-imageHeight)/2;
        
        if (x < 0) {
            x = 0;
        }
        if (y < 0) {
            y = 0;
        }
        
        f.style.left = String(x) + "px";;
        f.style.top = String(y) + "px";;
    }
}