JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <button>X</button>
    <textarea></textarea>
</div>

<br />

<div class="container">
    <button>X</button>
    <div>Text</div>
</div>

CSS

.container
{
    height: 220px;
    width: 220px;
    background-color: pink;	
}

.container > textarea
{
	width: 100%;
	height: 100%;
    background-color: cyan;
    box-sizing: border-box;
}

.container > div
{
	width: 100%;
	height: 100%;
    background-color: cyan;
}