.layout {
  width: 100%;

  display: grid;
  grid:
    "ColLeft ColMiddle ColRight" 5fr
    / 1fr 3fr 1fr;
  gap: 40px;
  grid-auto-flow: column;
}

.ColLeft { grid-area: ColLeft; }
.ColMiddle { grid-area: ColMiddle; }
.ColRight { grid-area: ColRight; }