JSFiddle - React, Tailwind, and code Playground

HTML

<div class="cnt">
  <div class="one">
  Center me
  </div>
  <div class="two">
  And me
  </div>
</div>

CSS

.cnt {
  display: flex;
}
.one {
  background: #ff0000;
  width: 300px;
}
.two {
  background: #00ff00;
  flex: 1;
}