.grid-container {
  display: grid;
  grid-template-columns: repeat(6, 1fr); 
  grid-gap: 1rem;
}

article:first-of-type {
  grid-row: 1 /  3;
  grid-column: 1 /  4; /* entre la line 1 et la line 4 */
}

article:nth-of-type(5) {
  grid-column: 4 / -1;
}

article:last-of-type {
  grid-column: 1 / -1;
}


/* Reset */

html {
  font-size: 62.5%;
  box-sizing: border-box;
}

* {
  box-sizing: inherit;
}

body {
  margin: 1rem;
  background: #fff;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif;
  font-size: 1.8rem;
  line-height: 1.5;
}

h1, h2 {
  font-weight: normal;
}

section {
  margin-bottom: 1em;
}

article {
  padding: 1rem;
  color: #fff;
}


article:nth-of-type(1) {
  background: orange;
}
article:nth-of-type(2) {
  background: hotpink;
}
article:nth-of-type(3) {
  background: olivedrab;
}
article:nth-of-type(4) {
  background: dodgerblue;
}
article:nth-of-type(5) {
  background: slategray;
}
article:nth-of-type(6) {
  background: tan;
}