body::after {
position: fixed;
top: 0;
left: 0;
content: '';
width: 100%;
height: 100%;
background-image: linear-gradient(
0deg,
black 0px,
black 1px,
transparent 1px,
transparent 100px
),
linear-gradient(
90deg,
black 0px,
black 1px,
transparent 1px,
transparent 100px
);
background-size: 50px 50px;
opacity: 0.1;
z-index: -1;
}