JSFiddle - React, Tailwind, and code Playground

HTML

<main>
  <div class="container">
    <div class="a1"></div>
    <div class="a1"></div>
    <div class="a1"></div>
    <div class="a1"></div>
  </div>
</main>

CSS

main {
    background-color: blue;
    width: 390px;
    display: flex;
    justify-content: center;
}

.container {
    background-color: red;
    display: inline-flex;
    flex-wrap: wrap;
}

.a1 {
  color: grey;
  width: 100px;
  height: 200px;
  background-color: green;
  border: 1px solid black;
}