JSFiddle - React, Tailwind, and code Playground

HTML

<html>

  <body>
    <div class="container">
      <div class="left">
        <textarea style="resize: both; max-width: 100%"></textarea>
      </div>
      <div class="right">
        something
      </div>
    </div>
  </body>

</html>

CSS

.container{
  display: flex;
  max-width: 100vw;
}
.left{
  flex: 1;
}
.right{
  flex: content;
}