.wrapper {
  max-width: 600px;
  margin: auto;
}

.gallery {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 0.5rem;
  grid-auto-flow: dense;
}

.gallery img {
  display: block;
  width: 100%;
  object-fit: cover;
  background-color: hsl(0 0% 90%);
}

.gallery-1by1 {
  aspect-ratio: 1 / 1;
  grid-column-end: span 1;
}