var winHeight = 0;
if(typeof(window.innerWidth) == 'number' ){
	//Non-IE
	winHeight = window.innerHeight;
} else if(document.documentElement && document.documentElement.clientHeight){
	//IE 6+ in 'standards compliant mode'
	winHeight = document.documentElement.clientHeight;
} else if( document.body && document.body.clientHeight){
	//IE 4 compatible
	winHeight = document.body.clientHeight;
}
if(winHeight == '') winHeight = 800;
winHeight = winHeight - 20;