<div class="board">
  <div class="square">1</div>
  <div class="square">2</div>
  <div class="square">3</div>
  <div class="square">4</div>
  <div class="square">5</div>
  <div class="square">6</div>
  <div class="square">7</div>
  <div class="square">8</div>
  <div class="square">9</div>
  <div class="square">10</div>
  <div class="square">11</div>
  <div class="square">12</div>
  <div class="square">13</div>
  <div class="square">14</div>
  <div class="square">15</div>
  <div class="square">16</div>
</div>
.board {
  display: grid;
  justify-content: center;
  align-content: center;
  grid-gap: 1rem;
  grid-template-columns: repeat(5, 10vw);
  grid-template-rows: repeat(5, 10vw);
}

.square:nth-child(1) {
  grid-row: 1;
  grid-column: 1;
}

.square:nth-child(2) {
  grid-row: 1;
  grid-column: 2;
}

.square:nth-child(3) {
  grid-row: 1;
  grid-column: 3;
}

.square:nth-child(4) {
  grid-row: 1;
  grid-column: 4;
}

.square:nth-child(5) {
  grid-row: 1;
  grid-column: 5;
}

.square:nth-child(6) {
  grid-row: 2;
  grid-column: 5;
}

.square:nth-child(7) {
  grid-row: 3;
  grid-column: 5;
}

.square:nth-child(8) {
  grid-row: 4;
  grid-column: 5;
}

.square:nth-child(9) {
  grid-row: 5;
  grid-column: 5;
}

.square:nth-child(10) {
  grid-row: 5;
  grid-column: 4;
}

.square:nth-child(11) {
  grid-row: 5;
  grid-column: 3;
}

.square:nth-child(12) {
  grid-row: 5;
  grid-column: 2;
}

.square:nth-child(13) {
  grid-row: 5;
  grid-column: 1;
}

.square:nth-child(14) {
  grid-row: 4;
  grid-column: 1;
}

.square:nth-child(15) {
    grid-row: 3;
    grid-column: 1;
  }

.square:nth-child(16) {
    grid-row: 2;
    grid-column: 1;
  }

/* Demo Specific Style */
.board {
  padding: 1em 0;
}

.square {
  background: #eaeaea;
  text-align: center;
  display: flex;
  align-items: center;
  justify-content: center;
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

This Pen doesn't use any external JavaScript resources.