wp-calypso/client/my-sites/store/components/d3/sparkline/style.scss

// Sparkline
// Making things sparky
.sparkline {
	.sparkline__line {
		fill: none;
		stroke: var(--color-primary);
		stroke-width: 1;
	}

	.sparkline__highlight {
		fill: var(--color-accent);
	}
}