CSS Grid Template Areas Builder

.layout {
  display: grid;
  grid-template-columns: 200px 1fr 200px;
  grid-template-rows: auto 1fr auto;
  grid-template-areas:
    "header header header"
    "nav    main   aside"
    "footer footer footer";
  gap: 16px;
  min-height: 100vh;
}

.layout > .header { grid-area: header; }
.layout > .nav { grid-area: nav; }
.layout > .main { grid-area: main; }
.layout > .aside { grid-area: aside; }
.layout > .footer { grid-area: footer; }

/* Below 768px, stack the areas in one column */
@media (max-width: 767px) {
  .layout {
    grid-template-columns: 1fr;
    grid-template-rows: auto;
    grid-template-areas:
      "header"
      "nav"
      "main"
      "aside"
      "footer";
  }
}