Customize drupal commerce checkout page
Customize Checkout Look and Feel

There was a recent commit that made the checkout process table-less in the Commerce Issue Que. It was reverted in favor of making such a large change to the codebase on a 2.x release. That code still exists and it's all possible using theme_ functions in your template.php


Go here
/modules/checkout/includes/commerce_checkout.pages.inc and look for functions that start with theme_
Add those functions that you
want to your template.php in your theme or a custom module 
Change the function word "theme" with your theme name or module name.
Make an obvious change or two 
Clear all caches and
then go through the checkout process.