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HTML/CSSBeginner#css#responsive
They let you name grid regions and visually map out a layout as an ASCII-like grid, then assign elements to named areas via grid-area, making complex layouts far more readable than raw line numbers.
.layout {
display: grid;
grid-template-areas:
"header header"
"sidebar main"
"footer footer";
}
.header { grid-area: header; }
.sidebar { grid-area: sidebar; }