jQuery.fn.center = function () {
	wrw = $('#wrapper').width() + 10;
	wrh = $('#wrapper').height() +10;
	wh = $(window).height();
	ww = $(window).width();
	if(wh > wrh && ww > wrh) {
    	this.css("position","absolute");
		this.css("margin","0 0 0 0");
    	this.css("top", ( $(window).height() - this.height()) / 2+$(window).scrollTop() + "px");
    	this.css("left", ( $(window).width() - this.width() ) / 2+$(window).scrollLeft() + "px");
    return this;
	}
}
$(document).ready(function() {
	$('#impressum').hide();
	$('#wrapper').center();
	$(window).resize(function(){
	  $('#wrapper').center();
	});
	
	
	$('#implink').toggle(function() {
	  $('#impressum').show();
	}, function() {
	  $('#impressum').hide();
	});
	
	// ***
	// Scrolling background
	// ***
 
	// height of background image in pixels
	var backgroundheight = 6000;
 
	// get the current minute/hour of the day
	var now = new Date();
	var hour = now.getHours();
	var minute = now.getMinutes();
 
	// work out how far through the day we are as a percentage - e.g. 6pm = 75%
	var hourpercent = hour / 24 * 100;
	var minutepercent = minute / 60 / 24 * 100;
	var percentofday = Math.round(hourpercent + minutepercent);
 
	// calculate which pixel row to start graphic from based
	// on how far through the day we are
	var offset = backgroundheight / 100 * percentofday;
 
	// graphic starts at approx 6am, so adjust offset by 1/4
	var offset = offset - (backgroundheight / 4);
 
	function scrollbackground() {
		// decrease the offset by 1, or if its less than 1 increase it by
		// the background height minus 1
   		offset = (offset < 2) ? offset + (backgroundheight - 2) : offset - 2;
		// apply the background position
   		$('body').css("background-position", "50% " + offset + "px");
   		// call self to continue animation
   		setTimeout(function() {
			scrollbackground();
			}, 50
		);
   	}
 
	// Start the animation
	scrollbackground();
	
	$('#cmyk').click(function(){
		$('#visual').attr("src","core/img/visual.png");
		bg = $('body').css("background-image");
		bg = bg.replace("gradient_bw.png", "gradient.png");
		$('body').css("background-image",bg);
		return false;
	});
	$('#mono').click(function(){
		$('#visual').attr("src","core/img/visual_desaturated.png");
		bg = $('body').css("background-image");
		bg = bg.replace("gradient.png", "gradient_bw.png");
		$('body').css("background-image",bg);
		return false;
	});
	
});