JSFiddle - React, Tailwind, and code Playground

HTML

<div class='newComment'>
   <div style='float:left;width:375px; background-color:#333;'>
     <textarea style='border:1px solid #888;overflow:auto' rows='3' cols='40'>comments </textarea>
   </div> 
   <div style='float:left;width:75px; background-color:#F50; overflow:hidden'> 
     <input type='submit' value='Add Comment'/> 
   </div>
 </div>

CSS

.newComment {
  position: relative;
  width:475px; 
  background-color:WHITE;
}