JSFiddle - React, Tailwind, and code Playground

HTML

<div class="block">

  <div class="item"></div>
  <div class="item"></div>

</div>

CSS

* {
  box-sizing: inherit;
}

html {
  box-sizing: border-box;
}
body {
  margin: 0;
  padding: 20px;
}

.block {
  display: flex;
  justify-content: center;
}
.item {
  width: 100px;
  height: 100px;
  margin: 0 10px;
  background: #f00;
}