body {
	background: url("https://mateuszslusarz.pl/img/background.jpg") no-repeat fixed center center / cover transparent ;
	-webkit-background-size: cover;
	-moz-background-size: cover;
	-o-background-size: cover;
	background-size: cover;
}

.center {
	display: block;
	margin-top: 100px;
	margin-left: auto;
    margin-right: auto;
}