Edit in JSFiddle

body {
background:
linear-gradient(-45deg, #fff 25%, transparent 25%, transparent 75%, #000 75%, #000) 0 0,
linear-gradient(-45deg, #000 25%, transparent 25%, transparent 75%, #fff 75%, #fff) 1em 1em,
linear-gradient(45deg, #000 17%, transparent 17%, transparent 25%, #000 25%, #000 36%, transparent 36%, transparent 64%, #000 64%, #000 75%, transparent 75%, transparent 83%, #000 83%) 1em 1em;
background-color: #fff;
background-size: 2em 2em;
}