JSFiddle - React, Tailwind, and code Playground

HTML

<div class="row">
  <div class="box">
     <div class="one">
       one
     </div>
  </div>
  <div class="box">
     <div class="two">
       two
     </div>
  </div>
</div>

CSS

.box {
  float: left;
  width:calc(50% - 1px);
  background: green;
  margin-right:1px
}

.one {
  height: 50px;
  
}
.two {
  height: 100px;
}