if (window.innerHeight) 
my_Height = (Math.round((window.innerHeight - 250) / 2));
else if (document.body.offsetHeight)
my_Height = (Math.round((document.body.offsetHeight - 250) / 2));
my_p = Math.round(my_Height/20);
while (nr <= my_p) {
document.write("<p class='pusher'>&nbsp;");
nr++;
}