12-span grid

Another classic: the 12-span grid. You can quickly write grids in CSS with the repeat() function. Using: repeat(12, 1fr); for the grid template columns gives you 12 columns each of 1fr.

.parent {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
}

.child-span-12 {
  grid-column: 1 / 13;
}

Now you have a 12 column track grid, you can place child elements on the grid. One way to do this would be to place them using grid lines. For example, grid-column: 1 / 13 would span all the way from the first line to the last (13th) and span 12 columns. grid-column: 1 / 5; would span the first four.

Another way to write this is by using the span keyword. With span, you set the starting line and then how many columns to span into from that starting point. In this case, grid-column: 1 / span 12 would be equivalent to grid-column: 1 / 13, and grid-column: 2 / span 6 would be equivalent to grid-column: 2 / 8.

.child-span-12 {
  grid-column: 1 / span 12;
}

 <div class="parent">
  <div class="span-12 section coral">Span 12</div>
  <div class="span-6 section green">Span 6</div>
  <div class="span-4 section yellow">Span 4</div>
  <div class="span-2 section blue">Span 2</div>
</div>

        .parent {
  display: grid;
  grid-template-columns: repeat(12, 1fr);
}

.span-12 {
  grid-column: 1 / span 12;
}

.span-6 {
  grid-column: 1 / span 6;
}

.span-4 {
  grid-column: 4 / span 4;
}

.span-2 {
  grid-column: 3 / span 2;
}

/* centering text */
.section {
  display: grid;
  place-items: center;
  text-align: center
}