Mostly front-end and design. We started on Big Cartel, then switched to Shopify. Original site wasn't responsive because it was from 2010. Built the first responsive version, badly, in January 2012 then re-design and re-built it in September 2012 to make better use of the space on big screens and improve performance.
Unfortunately that's about all I've written regarding the technical changes to the site over the years. It might have been a bit clearer if I had said re-designed and re-engineered the front-end if slightly less pithy. Hope that makes more sense.