woocommerce/plugins/woocommerce-admin/client/dashboard/store-performance/style.scss

/** @format */

.woocommerce-dashboard__store-performance {
	.woocommerce-card__body {
		padding: 0;
	}

	.woocommerce-summary {
		margin: 0;
		border-top: 0px;
		border-bottom: 0px;

		.woocommerce-summary__item {
			border-width: 0 1px 0 0;
		}
	}
}