.grid-container {
  display: grid;
  /* Define 3 columns and 2 rows, each 1fr wide/tall */
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(2, 1fr);
  width: 500px;
  height: 300px;
  background-color: #f0f8ff; /* Alice Blue */
  border: 2px dashed #a0d9ff;
  position: relative; /* Essential for z-index to work relative to container */
  font-family: sans-serif;
  font-size: 1.2em;
  font-weight: bold;
  color: white;
}

.grid-item {
  display: flex;
  justify-content: center;
  align-items: center;
  padding: 10px;
  border: 1px solid rgba(255,255,255,0.5);
  border-radius: 5px;
}

/* Item A: Spans columns 1 to 3 (covers first two columns) and row 1 */
.item-a {
  grid-column: 1 / 3;
  grid-row: 1 / 2;
  background-color: rgba(255, 99, 71, 0.8); /* Tomato */
  z-index: 1; /* Bring to front relative to other items in the same grid area */
}

/* Item B: Spans columns 2 to 4 (covers last two columns) and rows 1 to 3 (covers both rows) */
.item-b {
  grid-column: 2 / 4;
  grid-row: 1 / 3;
  background-color: rgba(60, 179, 113, 0.8); /* Medium Sea Green */
  z-index: 2; /* Bring even further to front */
}

/* Item C: Standard placement, but will be partially hidden by Item B due to z-index */
.item-c {
  grid-column: 1 / 2;
  grid-row: 2 / 3;
  background-color: rgba(70, 130, 180, 0.8); /* Steel Blue */
  z-index: 0;
}

/* Example HTML structure:
<div class="grid-container">
  <div class="grid-item item-a">Layer 1 (Item A)</div>
  <div class="grid-item item-b">Layer 2 (Item B)</div>
  <div class="grid-item item-c">Layer 3 (Item C)</div>
</div>
*/