<header>
	<h1>Fractions of fractions</h1>
	<p>The sum of our flex factors is less than 1, so our grid items take up the equivalent proportion of the leftover space and do not expand to fill it.</p>
</header>
<div class="grid">
	<div class="item"></div>
	<div class="item"></div>
	<div class="item"></div>
</div>

* {
	box-sizing: border-box;
}

body {
	margin: 0;
}

header {
	padding: 1rem;
}

.grid {
	display: grid;
	grid-template-columns: repeat(3, 0.2fr);
	grid-template-rows: 300px;
	column-gap: 40px;
}

.item {
	background-color: blue;
}