<div class="gradient-pattern"></div>

body {
  padding: 1.5rem;
}

.gradient-pattern {
  background-color: #fff;
  background-image: linear-gradient(
      45deg,
      #333 25%,
      transparent 25%,
      transparent 75%,
      #333 75%,
      #333
    ),
    linear-gradient(
      -45deg,
      #333 25%,
      transparent 25%,
      transparent 75%,
      #333 75%,
      #333
    );
  background-size: 50px 50px;
  height: 250px;
}