WooCommerce 2-column checkout page

2-col-woo-checkout.css

/* 2-col WooCommerce Checkout - tested in BB Theme, Generate Press, TwentyTwelve, TwentyThirteen, TwentyFourteen TwentyFifteen, TwentySixteen, TwentySeventeen and TwentyNineteen */

/* TwentyTwenty and TwentyTwentyOne already have this CSS or similar */

@media(min-width:768px) {
	.woocommerce .col2-set .col-1, 
	.woocommerce-page .col2-set .col-1 {
		width: 90%;
	}

	#customer_details {
		display: flex;
		flex-flow: column nowrap;
		float: left;
		width: 50%;
	}

	#customer_details .col-2 {
		width: 90%;
		margin-top: 20px;
	}

	#order_review,
	#order_review_heading {
		width: 50%;
		float: left;
		clear: none;
	}
}