.item1 { grid-area: header; }
.item2 { grid-area: menu; }
.item3 { grid-area: main; }
.item4 { grid-area: right; }
.item5 { grid-area: footer; }
.item6 { grid-area: extra; }

.grid-container {
  display: grid;
  grid-template-areas:
  "header header header header header header"
  "menu main main main right right"
  "extra extra extra extra extra extra"
  "footer footer footer footer footer footer";
  grid-gap: 100px;
  background-color: #000000;
  padding: 50px;
  grid-template-rows: 15% 8% 20% 9% 5% 5%;
  grid-row: 1 / span 2;
}

.grid-container > div {
  background-color: rgba(255, 255, 255, 0.8);
  text-align: center;
  padding: 20px 0;
  font-size: 30px;
}