JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
  <div class="main">One</div>
  <div class="side">Two</div>
</div>

CSS

.container{
  width: 100%
}
.main{
  /* padding: 30px; */
  background-color: red;
  width: 70%;
   float: left;
}
.side{
   /* padding: 10px; */
  background-color: yellow;
  width:30%;
   
}