body{
	background-image: url('/conf-data/PMA2018/images/Rysunek-t%C5%82o-optimized.jpg');
	background-size: cover;
	background-position: center center;
}
body::after{
	content: '';
	position: fixed;
	top: 0;
	left: 0;
	right: 0;
	bottom: 0;
	background: rgba(0,0,0,0.2);
	z-index: -1000;
}