reveal.js/css/layout.scss

/**
 * Layout helpers.
 */

// Stretch an element vertically based on available space
.reveal .stretch,
.reveal .r-stretch {
	max-width: none;
	max-height: none;
}

.reveal pre.stretch code,
.reveal pre.r-stretch code {
	height: 100%;
	max-height: 100%;
	box-sizing: border-box;
}

// Stack multiple elements on top of each other
.reveal .r-stack {
	display: grid;
}

.reveal .r-stack > * {
	grid-area: 1/1;
	margin: auto;
}

// Horizontal and vertical stacks
.reveal .r-vstack,
.reveal .r-hstack {
	display: flex;
}

.reveal .r-vstack {
	flex-direction: column;
}

.reveal .r-hstack {
	flex-direction: row;
}

.reveal .items-center {
	align-items: center;
}

.reveal .justify-center {
	justify-content: center;
}