woocommerce/plugins/woocommerce-blocks/assets/js/blocks/legacy-template/editor.scss

.wp-block-woocommerce-legacy-template__placeholder-copy {
	max-width: 900px;
	margin-bottom: 30px;
}

.wp-block-woocommerce-legacy-template__placeholder-wireframe {
	width: 100%;
	height: 250px;
	background: #e5e5e5;

	@media only screen and (min-width: 768px) {
		height: auto;
		background: transparent;
	}
}

.wp-block-woocommerce-legacy-template__placeholder .wp-block-woocommerce-legacy-template__placeholder-image {
	display: none;
	width: 100%;
	height: auto;

	@media only screen and (min-width: 768px) {
		display: block;
	}
}