JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="one">one</div>
  <div class="two">two</div>
</div>

CSS

.container {
  display: flex;
}

.container > div {
  padding: 6px;
}

.one {
  background: #fcc9e5;
  flex-basis: 20%;
}

.two {
  background: #ecaef9;
  flex: 1;
}