var setMiddle = function()
{
    var v = 0;
    var middle = function()
    {
        var a1 = getPageSize()[3];
        var a2 = document.body.offsetHeight - v;
        if(a1 > a2)
        {
            v = ((a1 - a2) / 2);
            
            document.body.style.paddingTop = v + 'px';
        }
        else
        {
            document.body.style.paddingTop = '0';
            v = 0;
        }
    }
    document.body.onresize = middle;
    middle();
}
function getPageSize()
{
    var xScroll, yScroll;
    if (window.innerHeight && window.scrollMaxY)
    {
        xScroll = document.body.scrollWidth;
        yScroll = window.innerHeight + window.scrollMaxY;
    }
    else if (document.body.scrollHeight > document.body.offsetHeight)
    {
        xScroll = document.body.scrollWidth;
        yScroll = document.body.scrollHeight;
    }
    else
    {
        xScroll = document.body.offsetWidth;
        yScroll = document.body.offsetHeight;
    }
    var windowWidth, windowHeight;
    if (self.innerHeight)
    {
        windowWidth = self.innerWidth;
        windowHeight = self.innerHeight;
    }
    else if(document.documentElement && document.documentElement.clientHeight)
    {
        windowWidth = document.documentElement.clientWidth;
        windowHeight = document.documentElement.clientHeight;
    }
    else if (document.body)
    {
        windowWidth = document.body.clientWidth;
        windowHeight = document.body.clientHeight;
    }
    if(yScroll < windowHeight)
    {
        pageHeight = windowHeight;
    }
    else
    {
        pageHeight = yScroll;
    }
    if(xScroll < windowWidth)
    {
        pageWidth = windowWidth;
    }
    else
    {
    pageWidth = xScroll;
    }
    arrayPageSize = new Array(pageWidth,pageHeight,windowWidth,windowHeight)
    return arrayPageSize;
}