Tailwind CSS class .grid-flow-row-dense

<div class="grid grid-cols-3 grid-flow-row-dense gap-2">
  <div class="text-center bg-teal-400">1</div>
  <div class="text-center bg-teal-400">2</div>
  <div class="text-center col-span-2 bg-teal-400">3</div>
  <div class="text-center bg-teal-400">4</div>
  <div class="text-center bg-teal-400">5</div>
  <div class="text-center bg-teal-400">6</div>
</div>

.grid-flow-row-dense {
    grid-auto-flow: row dense;
}