The site actually works on your phone.

We tested the site on actual phones and fixed what didn't work. The top bar doesn't overflow. The buttons are big enough to tap. The message bar stays visible when you scroll. Pages don't scroll sideways.

This sounds small, but a lot of shops have sites that technically work on phones and functionally don't. Buttons too small to hit. Text that doesn't fit. Stuff that looks fine on a computer and falls apart when you hold it in your hand. We tested on phones and fixed everything that broke.

It's the difference between a site that adapts to your phone and a site that actually works. We chose the latter.