JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="container-item">1</div>
  <div class="container-item">2</div>
  <div class="container-item">3</div>
</div>

CSS

.container {
  display: flex;
  flex-direction: row;
  height: 100px;
}

.container-item {
  border: 1px solid red;
  flex-grow: 1
}