body {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  width: 100%;
  height: 100dvh;
  display: flex;
  align-items: center;
  justify-content: center;
}

section {
  width: max-content;
  display: grid;
  grid-template-columns: 1fr 1fr 1fr;
  grid-template-rows: 1fr 1fr 1fr;
  position: relative;
  background-color: black;
  gap: 10px;
}

div {
  width: 150px;
  height: 150px;
  content: "";
  background-color: rgb(255, 255, 255);
  display: inline-block;
  box-shadow: inset 0 -10px 0 #ffffff, inset 10px 0 0 #ffffff,
    inset 0 10px 0 #ffffff, inset -10px 0 0 #ffffff;
}

section.before0::before,
section.before3::before,
section.before6::before,
section.before0vertical::before,
section.before1vertical::before,
section.before2vertical::before,
section.before1diagonal::before,
section.before2diagonal::before {
  content: "";
  background-color: burlywood;
  position: absolute;
}

section.before0::before,
section.before3::before,
section.before6::before {
  width: 100%;
  height: 8px;
}

section.before0::before {
  top: 60px;
}

section.before3::before {
  top: 220px;
}

section.before6::before {
  top: 380px;
}

section.before0vertical::before,
section.before1vertical::before,
section.before2vertical::before {
  width: 8px;
  height: 470px;
}

section.before0vertical::before {
  left: 70px;
}

section.before1vertical::before {
  left: 230px;
}

section.before2vertical::before {
  left: 390px;
}

section.before1diagonal::before,
section.before2diagonal::before {
  width: 150%;
  height: 8px;
  top: 235px;
  left: -110px;
}

section.before1diagonal::before {
  transform: rotate(45deg);
}

section.before2diagonal::before {
  transform: rotate(-45deg);
}

@media (max-width: 487px) {
  div {
    width: 100px;
    height: 100px;
  }

  section.before0::before {
    top: 50px;
  }

  section.before3::before {
    top: 150px;
  }

  section.before6::before {
    top: 250px;
  }

  section.before0vertical::before,
  section.before1vertical::before,
  section.before2vertical::before {
    width: 8px;
    height: 320px;
  }

  section.before0vertical::before {
    left: 50px;
  }

  section.before1vertical::before {
    left: 160px;
  }

  section.before2vertical::before {
    left: 270px;
  }

  section.before2diagonal::before {
    width: 150%;
    height: 8px;
    top: 185px;
    left: -110px;
  }
  section.before1diagonal::before {
    width: 150%;
    height: 8px;
    top: 135px;
    left: -110px;
  }
}