Sandbox

style.css
setup.css
index.html

/* Setup styles in the other file. */

section {
	display: flex;
}

div {
	flex-grow: 1;
}

div:nth-child(1) {
	align-self: stretch;
	/* This is the default. */
}

div:nth-child(2) {
	background-color: lightsalmon;
	align-self: flex-start;
}

div:nth-child(3) {
	background-color: crimson;
	align-self: center;
}

div:nth-child(4) {
	background-color: hotpink;
	align-self: flex-end;
}

body {
	font-family: sans-serif;
	padding: 20px;
}

div {
	background-color: tomato;
	border-bottom: 2px solid firebrick;
	border-right: 2px solid firebrick;
	padding: 5px;
}

section {
	background-color: gold;
	height: 100px;
}

section:not(:first-child) {
	margin-top: 20px;
}

<!doctype html>
<html>
	<head>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, initial-scale=1">
		<link href="../assets/reset.css" rel="stylesheet">
		<link href="setup.css" rel="stylesheet">
		<link href="style.css" rel="stylesheet">
	</head>
	<body>
		<section>
			<div>
				<p>Item 1</p>
			</div>
			<div>
				<p>Item 2</p>
			</div>
			<div>
				<p>Item 3</p>
			</div>
			<div>
				<p>Item 4</p>
			</div>
		</section>
	</body>
</html>