Auto-hide Page Sections with HTML and CSS

This code creates a page that is broken up into sections which reveal themselves only as the user clicks on each of them. This is to maximize the vertical space on the page.

<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<meta name="viewport" content="width=device-width, initial-scale=1.0">
	<meta http-equiv="X-UA-Compatible" content="ie=edge">
	<title>Auto-hide without JavaScript</title>
	<style>
		body {
			font-family: sans-serif;
			font-size: 14px;
			color: #333;
			background-color: #fff;
		}
		h1 {
			padding: 1%;
			background-color: #631;
		}
		h1 a {
			text-decoration: none;
			color: gold;
		}
		.auto-hide {
			width: 100%;
		}
		.auto-hide section {
			position: relative;
			padding: 15px 0;
		}
		.auto-hide section a {
			display: block;
			text-decoration: none;
			color: inherit;
			border-bottom: 2px solid #999;
		}
		.auto-hide .sub a,
		.auto-hide .sub span {
			display: block;
			border-bottom: none;
			margin: 15px 30px;
			text-decoration: none;
			color: navy;
		}
		.auto-hide .sub {
			overflow: hidden;
			transition: max-height .5s;
			max-height: 0vh;
		}
		.auto-hide section:target .sub {
			overflow: auto;
			max-height: 100vh;
		}
		.auto-hide section a::after {
			content: "";
			width: 0;
			height: 0;
			position: absolute;
			right: 16px;
			top: 25px;
			margin-top: -3px;
			border-width: 0 6px 6px 6px;
			border-style: solid;
			border-color: #999 transparent;
		}
		.auto-hide section:target a::after {
			border-width: 6px 6px 0 6px;
		}
	</style>
</head>
<body>
	<h1><a href="#!">Up's Delivery Service, Corp.</a></h1>
	<div class="auto-hide">
		<section id="updates">
			<a href="#updates">Get Email Updates</a>
			<div class="sub">
				<span>All Events</span>
				<span>Delivered</span>
				<span>In transit</span>
				<span>Acceptance</span>
			</div>
		</section>
		<section id="tracking">
			<a href="#tracking">Tracking History</a>
			<div class="sub">
				<span>Jan 3 - Delivered</span>
				<span>Jan 2 - In transit</span>
				<span>Jan 1 - Delayed</span>
				<span>Dec 31 - Acceptance</span>
			</div>
		</section>
		<section id="product">
			<a href="#product">Product Details</a>
			<div class="sub">
				<span>Ground - 5 Day</span>
			</div>
		</div>
	</div>
</body>
</html>

Coding Video

https://youtu.be/ovRelbR8xyE