mobile-first confusions???? :(
Okay, we sized the page to the content of the iPhone, but are we going to need to resize back to fit the laptop?
Rune Andreas Nielsen5,342 Points
When you do mobile-first development on the web, it means that you design the layout for the mobile before, bigger size devices.
There are a few benefits when you do this. One of them is that it is usually easier to "grow" a design from mobile to desktop than it is to move from desktop to mobile. The other one is that you will have less CSS executing on the mobile size than you would if you did desktop to mobile.
I hope this answers your question.
I always design for desktop first as I find it easier, but I also test and consider mobile-first as I go. When I design a website, I do that first in Affinity (great design tool, by the way) and design the desktop view alongside the mobile view, side by side. That way, I can see both design layout in one view.