<div class="container">
  <p class="item">.item</p>
</div>
.container {
  display: grid;
  gap: 10px;
  grid-template-columns: 1fr 1fr 1fr;
  grid-template-rows: 2rem 2rem 2rem;
}

.item {
  grid-column: 2 / span 1;
  grid-row: 2 / span 2;
}


/* etc: */

body {
  margin: 1.5em;
  font-size: 130%;
}

.item {
  background: #b3e888;
  padding: 1em;
  margin-top: 0;
  margin-bottom: 0;
  font-family: monospace;
  text-align: center;
  border: 1px solid darkgreen;
  /* "border-collapse" hack */
  margin-left: -1px;
  margin-top: -1px;
}

.container {
  border: 5px solid black;
  padding: 1em;
  margin-bottom: 2em;  
}

External CSS

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External JavaScript

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