function setMiddle() {
	var height = $(window).height() - $(".upper").offset().top - $(".upper").height() - $(".lower").height() - $(".footer").height();
	$(".middle").height(height);
	$(".content").height(height);
}

$(document).ready(function() {
	var img1 = new Image();
	img1.src = "/images/button_green.png";
	
	var img2 = new Image();
	img2.src = "/images/button_orange.png";
	
	var img3 = new Image();
	img3.src = "/images/button_pink.png";
	
	var img4 = new Image();
	img4.src = "/images/button_purple.png";

	$(".footer").css("bottom",-$(".footer").height());
	setMiddle();
	
	$(window).resize(function() {
		setMiddle();
	});
});