JSFiddle - React, Tailwind, and code Playground

HTML

<div class="wrapper">
<div class="box1">

</div>
<div class="box2">

</div>
</div>

CSS

.wrapper {
  display: flex;
  flex-wrap: wrap;
}

.box1 {
  margin-right: 60px;
  flex: 1 1 400px;
  height: 100px;
  background: blue;
}

.box2 {
  flex: 1 1 200px;
  height: 100px;
  background: yellow;
}