JSFiddle - React, Tailwind, and code Playground

HTML

<div id="grid">
  <div></div>
  <div></div>
</div>

CSS

#grid {
  display: grid;
  grid-template-columns: 60% minmax(250px, 1fr);
  grid-gap: 1em;
}

#grid > div {
  background-color: #ccddaa;
  padding: 10px;
}