:root{
	--HEADER_WIDTH: 200px
}

.HEADER{
	position: fixed;
	top: 0px;
	left: 0px;

	width: var(--HEADER_WIDTH);
	height: 100vh;

	border-right: solid 1px;
}

.CONTENTS{
	position: fixed;
	top: 0px;
	left: calc(var(--HEADER_WIDTH) + 1px);

	width: calc(100vw - var(--HEADER_WIDTH));
	height: 100vh;
}