JSFiddle - React, Tailwind, and code Playground

HTML

<div class="container">
    <div class="div-textarea">
	    <textarea id="txtarea" placeholder="This  is a textarea" style="width: 98%; text: no-wrap"></textarea>
	</div>
	<div class="div-submit">
		<input type="submit" value="Post">
	</div>
</div>

CSS

.container{
    background-color: green;
    width: 100%;
    margin: 0;
}

.div-textarea{
    float: left;
    background-color: blue;
    opacity: 0.5;
    width: 90%;
}

.div-submit{
    float: left;
    background-color: red;
    opacity: 0.5;
    width: 5%;
}