WordPress/wp-content/themes/twentynineteen/sass/media/_galleries.scss

.gallery {
	display: flex;
	flex-flow: row wrap;
	justify-content: center;
	margin-bottom: calc(1.5 * #{$size__spacing-unit});
}

.gallery-item {
	display: inline-block;
	margin-right: 16px;
	margin-bottom: 16px;
	text-align: center;
	vertical-align: top;
	width: 100%;

	// Loops to enumerate the classes for gallery columns.
	@for $i from 2 through 9 {
		.gallery-columns-#{$i} & {
			max-width: calc((100% - 16px * #{ $i - 1 }) / #{ $i });

			&:nth-of-type(#{$i}n+#{$i}) {
				margin-right: 0;
			}
		}
	}

	&:last-of-type {
		padding-right: 0;
	}
}

.gallery-caption {
	display: block;
	font-size: $font__size-xs;
	@include font-family( $font__heading );
	line-height: $font__line-height-pre;
	margin: 0;
	padding: ( $size__spacing-unit * .5 );
}

.gallery-item > div > a {
	display: block;
	line-height: 0;

	// Accessibility
	box-shadow: 0 0 0 0 transparent;

	&:focus {
		box-shadow: 0 0 0 2px rgba( $color__link, 1 );
	}
}