.holy-grail-layout {
  display: grid;
  grid-template-columns: 1fr;
  grid-template-rows: auto 1fr auto auto auto; /* Header, Left, Main, Right, Footer for mobile */
  grid-template-areas:
    "header"
    "left-sidebar" /* Stacked for mobile */
    "main"
    "right-sidebar" /* Stacked for mobile */
    "footer";
  min-height: 100vh;
}

.header { grid-area: header; background-color: #f0f0f0; padding: 20px; }
.main-content { grid-area: main; background-color: #fff; padding: 20px; }
.left-sidebar { grid-area: left-sidebar; background-color: #e0e0e0; padding: 20px; }
.right-sidebar { grid-area: right-sidebar; background-color: #d0d0d0; padding: 20px; }
.footer { grid-area: footer; background-color: #f0f0f0; padding: 20px; }

@media (min-width: 768px) {
  .holy-grail-layout {
    grid-template-areas:
      "header header header"
      "left-sidebar main right-sidebar"
      "footer footer footer";
    grid-template-columns: 200px 1fr 200px; /* Example: fixed sidebars, flexible main */
    grid-template-rows: auto 1fr auto; /* Only 3 rows for desktop */
  }
}