woocommerce/plugins/woocommerce-blocks/assets/js/blocks/cart-checkout/checkout/editor.scss

.editor-styles-wrapper .wp-block h4.wc-block-checkout-step__title {
	font-size: 16px;
	line-height: 24px;
	margin: 0 $gap-small 0 0;
}

.wc-block-checkout__controls-text {
	color: #999;
	font-style: italic;
}