JSFiddle - React, Tailwind, and code Playground

HTML

<div id='wrapper'>
  <div id='left-block'>
    <div class='elmt'>
    elmt 1
    </div>
    <div class='elmt'>
    elmt 2
    </div>
    <div class='elmt'>
    elmt 3
    </div>
     <div class='elmt'>
    elmt 4
    </div>
    <div class='elmt'>
    elmt 5
    </div>
    <div class='elmt'>
    elmt 6
    </div>
        <div class='elmt'>
    elmt 7
    </div>
    <div class='elmt'>
    elmt 8
    </div>
    <div class='elmt'>
    elmt 9
    </div>
  </div>
  <div id='right-block'>
      Lorem ipsum dolor sit amet, consectetur adipisicing elit. Voluptas minus commodi repellat voluptatum odit quos excepturi fugiat quia distinctio harum pariatur inventore possimus minima sequi, enim eius, cupiditate, perferendis accusantium.
  </div>
  <div style='clear:both'>
  
  </div>
</div>

CSS

#left-block{
  float:left;
  width:30%;
  background-color:red;
  overflow:auto;
}

#right-block{
  float:right;
  width:70%;
  background-color:green;
}