It’s not about the device.
ethanmarcotte.com →

Ethan Marcotte:

Let me start by saying I generally avoid terms like “mobile,” “tablet,” and “desktop” in my work. It’s not that they’re bad; it’s because they’re broad. In my experience, terms like these confuse more than they clarify. Ask a roomful of clients or stakeholders to define “mobile,” and you’ll get a roomful of slightly different responses.

What I think is helpful, though, is breaking down the specific conditions or features that’ll cause our designs to adapt.