JSFiddle - React, Tailwind, and code Playground

HTML

<div>
    <textarea></textarea>
</div>

CSS

div{
    height: 200px;
    width: 300px;
    background: red;
}
textarea{
    height: 100%;
    width: 100%;
   -webkit-box-sizing: border-box; /* Safari/Chrome, other WebKit */
	-moz-box-sizing: border-box;    /* Firefox, other Gecko */
	box-sizing: border-box;         /* Opera/IE 8+ */
}