* {
  margin: 0;
}

.container div {
  background-color: gray;
  border: 2px solid;
  border-radius: 5px;
  font-size: large;
  padding: 10px;
  margin: 10px;

  @media screen and (width<500px) {
    padding: 2px;
    margin: 2px;
  }
}

.container {
  display: grid;
  grid-template-columns: repeat(3, minmax(100px, auto));
  grid-template-rows: repeat(3, minmax(100px, auto));

  > :nth-last-child(1) {
    grid-column: 2/4;
    grid-row: 2/4;

    display: grid;
    grid-template-columns: subgrid;
    grid-template-rows: subgrid;
  }

  > :nth-child(4) {
    grid-row: 2/4;
  }
}