JSFiddle - React, Tailwind, and code Playground

HTML

<body>
		<div id="contenedor">
			<div id="cajita">

			</div>				
		</div>
	</body>

CSS

#cajita {
		border: 1px dashed;
		height: 40px;
		width: 120px;
		margin:312px auto 0 auto;
		}

		#contenedor {
		background-color: grey;
		height: 665px; 
		width: 960px; 
		margin-left:auto; 
		margin-right:auto;
		}