JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="child one">
    Child One
  </div>
  
  <div class="child two">
    Child Two
  </div>
</div>

CSS

div {
  border: 1px solid;
}

.container {
  display: flex;
}

.child.one {
  flex: 1 1 10em;
  color: green;
}

.child.two {
  flex: 2 2 10em;
  color: purple;
}