JSFiddle - React, Tailwind, and code Playground

HTML

<body>	  
    <div class="content">
      <div id="left">
        <p>Click me to change size</p>
      </div>
      <div class="right">  
        <p>This</p>
        <p>is</p>
        <p>what</p>
        <p>you are looking for!</p>
      </div>
    </div>
    </body>

CSS

.content #left{
        float:left;
        width:100px;
        background-color:green;
      }
      .content .right{
	    overflow: auto; 
        background-color:red;
      }

JavaScript

document.getElementById("left").onclick = changeSize;
function changeSize ()
{
    this.style.width = "200px";
}