JSFiddle - React, Tailwind, and code Playground

HTML

<div class="flex">
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <div></div>
  <aside></aside>
</div>

CSS

.flex {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-auto-rows: 25px;
  grid-gap: 5px;
  margin: auto;
  max-width: 120px;
}

aside {
  grid-column: 4;
  grid-row: 1 / span 2;
  background: blue;
}

.flex > div {
  background: red;
}