JSFiddle - React, Tailwind, and code Playground

HTML

<div id="wrapper">
  <div id="w30">  
    width 30%
  </div>
  <div id="w70">  
    width 70%
  </div>

</div>

CSS

#wrapper{
  width:100%;
}
#w30{
  background:yellow;
  display:inline-block;
  width:30%;
}

#w70{
  background:pink;
  display:inline-block;
  width:70%;
}