h1 {
  background-color: bisque;
  padding: 20px;
  text-align: center;
  color: tomato;
}
img {
  width: 100%;
  height: 100%;
}
section {
  margin-bottom: 50px;
}
.row {
  height: 400px;
  display: flex;
  gap: 5px;
  margin-bottom: 5px;
}
.row > div {
  flex: 1;
}
.virtical-collage img {
  height: calc((100% - 5px) / 2);
}
.square-collage {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 5px;
}
/* responsive  media query */
/* small device */
@media screen and (max-width: 576px) {
  .row {
    flex-direction: column;
    height: auto;
  }
  .square-collage {
    grid-template-columns: repeat(1, 1fr);
  }
}
/* medium device */
@media screen and (min-width: 576px) and (max-width: 992px) {
  .row {
    flex-direction: column;
    height: auto;
  }
}