JSFiddle - React, Tailwind, and code Playground

HTML

<div>
  <div class="red">
    <div></div>
    <div></div>
    <div></div>
    <div></div>
    <div></div>
  </div>
  <div class="green">
    <div></div>
  </div>
</div>

CSS

body > div {
  display: flex;
  width: 34rem;
  justify-content: space-between;
  border: 1px solid black;
}

body > div > div {
  display: flex;
  flex-flow: row wrap;
}

body > div > div.red {
  background: rgba(255, 0, 0, .1);
  max-width: 345px;
}

body > div > div.green {
  background: rgba(0, 255, 0, .1);
  flex-shrink: 0;
}

body > div > div > div {
  margin: 1rem;
  height: 5rem;
  width: 5rem;
  background: rgba(0, 0, 0, .1);
}