var this_page = null;
var page_width = 620;

function nextPage() {
	var np = this_page.next();
	animate(this_page, -1);
	animate(np, 0);
	this_page = np;
	$("#page_container").height(this_page.height()+20);
}

function prevPage() {
	var pp = this_page.prev();
	animate(this_page, 1);
	animate(pp, 0);
	this_page = pp;
	$("#page_container").height(this_page.height()+20);
}

function animate(page, val) {
	page.animate({
		left : (val*page_width)+"px"
	}, 500);
}

$(document).ready(function() {
	this_page = $("#first_page");
	$("#page_container").height(this_page.height()+20);
});