You can't call it "mobile first" if you're designing desktop first
Huh?
Another way to put it: Designing mobile-first means, uh, actually designing the mobile layout first.
Does the above sound abolutely insane to you? It does to me.
You may have a hard time believing this — I have a hard time believing this: I've ocasionally worked with some brand teams who say, "We designed this 'mobile-first'," and then they only show desktop art. The first time I heard/saw this, it was in front of clients, so I kept my mouth shut — which wasn't easy! If we're only looking at desktop, then what on earth do they mean when they say they did mobile first?
It's difficult to believe, but there are people who treat the phrase "mobile first" as just sort of a buzzword, meaning simply, "We were totally thinking about mobile when we designed this" — when what they've designed is just a desktop layout. This is absolutely bonkers. They've reduced "mobile first" to a linguistic symbol that does not actually mean mobile first. It's frankly unbelievable. But I've seen it happen more than once.
I've also heard people reference this bullshit concept called "mobile forward" or "mobile focused" design — they're showing you a desktop layout and telling you it will definitely be a good mobile experience because, like, they thought about it in their brains while they were designing. Basically saying, "We recognize that mobile is extremely important — important enough that we're bragging about it to you so we can look smart — but we didn't bother to actually lay it out." This is garbage. It's lazy — it's downright dishonest, really. We absolutely must do better than this.
When designing responsive websites (and emails!) we must actually, physically lay out the mobile view first. Put in the effort to make that experience perfect, and then we can easily extend for desktop. This is the only right way to design responsive media.
– Manning
Questions/comments? Feel free to contact me at manning@manningkrull.com. I update these articles pretty frequently — best practices evolve over time as the world of digital quickly changes, and I always welcome insights from others.