$(document).ready(function (){	

divresize();
$(window).resize(function(){
	divresize();
});
			
function divresize(){
	var windowheight = $(window).height(); 
		if(windowheight > 620){
			var windowheight = $(window).height(); 
			var contentheight = "256";
			var divheight = (windowheight - contentheight);
			$('#clouds').css("top", divheight + "px");
		}else{
			$('#clouds').css("top", "400px");
		}
	}
});