body{
background:
radial-gradient(circle at 100% 50%, transparent 20%, rgba(255,255,255,.3) 21%, rgba(255,255,255,.3) 34%, transparent 35%, transparent),
radial-gradient(circle at 0% 50%, transparent 20%, rgba(255,255,255,.3) 21%, rgba(255,255,255,.3) 34%, transparent 35%, transparent) 0 -50px;
background-color: slategray;
background-size:75px 100px;
}