by loren_d_c » Wed Jan 20, 2021 12:37 pm
If you're using the [-- SC_Address --] tag that creates table-formatted address fields, then you should be able to uncheck the box "Billing Address displayed above Shipping Address" in Commerce > Order System > Checkout and it will put the tables side-by-side on the Checkout screen.
Almost all the newer responsive templates use [-- SC_Address_V2 --] which uses DIVs and SPANs around the address fields, and the layout is then determined by how you style it in your CSS. This is better when you want the address fields side by side for a larger screen, but on a smaller screen it could responsively switch to one above the other, whereas the table-based layout would just force the user to have to scroll over to see the shipping address fields.
-Loren