CSS Grid Template Areas

.container {
  display: grid;
  grid-template-areas:
    "header header header"
    "sidebar main main"
    "footer footer footer";
  grid-template-rows: repeat(3, 1fr);
  grid-template-columns: repeat(3, 1fr);
  gap: 8px;
}

.header { grid-area: header; }
.sidebar { grid-area: sidebar; }
.main { grid-area: main; }
.footer { grid-area: footer; }