Here is a simple CSS-only solution, using linear gradients:
html,
body,
.grid {
height: 100%;
width: 100%;
margin: 0;
}
.grid {
background-image:
repeating-linear-gradient(#ccc 0 1px, transparent 1px 100%),
repeating-linear-gradient(90deg, #ccc 0 1px, transparent 1px 100%);
background-size: 71px 71px;
}
<div class="grid"></div>