	border-radius: 5px;
		padding: 20px;
		font-size: 150%;

	}

	.header {
		background-color: #999;
	}

	.overlay {
		background-color: red;
		z-index: 10;
		grid-column: content-start / content-end;
		grid-row: header-start / content-end;
	}

   </style>
</head>

 <body>

	 <div class="wrapper">
	 	<div class="box header">Header</div>
		<div class="box sidebar">Sidebar</div>
		<div class="box content">Content</div>
		<div class="overlay">overlay</div>
	</div>
</body>
</html>
