One of the first questions a client might ask you when you start talking about his new website site is “Will it be responsive?”. And the answer to that question will more often than not be “Yes, it will”. Especially now that Google will penalize websites that aren’t mobile friendly it’s important that you make sure that your site works well on mobile devices. How do you approach responsive webdesign in a good way? Even though I am not a designer I’d say mobile-first.

Different approaches to responsive web design

When you’re doing a responsive webdesign there’s a couple of ways to do it. Some people use Photoshop and design three different versions of their website, one for mobile phones, one for tablets and one for the desktop. Others just make one of these three and design the rest during development in the browser.

If you only design one of the three big options, which one should it be? And when you start to build the website, where do you start? Do you do the desktop version first since it’s easier for you as a developer? Or do you start with the tablet version because it’s in the middle of the spectrum? Or do you let the client decide and start with the one that makes them the happiest?

These are just a few of the options you have when you’re doing responsive web design, there isn’t a way that is forced upon you by anybody and you’re free to choose whatever you feel is most efficient. But in practice there seems to be one approach in the development phase that works every time for me. That approach is mobile-first.

What is mobile-first?

Mobile-first means exactly what you probably think it means, it’s when you start your process with the mobile phone. Ideally you will start both the design and the development phase by thinking about mobile straight away. My experience is, however, that clients prefer to see designs for how the website will look on a big screen with all the bells and whistles you might add. So designers tend to not really work from a mobile first perspective because they focus on what the client likes to see. This probably doesn’t apply to every designer and every client but it does apply to most designers and clients I’ve worked with.

When you enter the development phase, the approach you take is in your hands, you can decide where to start. And deciding to start mobile first isn’t just a matter of preference. There are very valid reasons to approach the development phase from a mobile-first perspective.

Why mobile-first?

When you are building a responsive website there’s a lot of things to consider, how does this look on a screen that is X wide? Should module Y be visible on that screen? Thinking about everything for every screen is overwhelming, there’s so much going on and you get so little for free when you’re building a website. So you’re going to have to start somewhere and I prefer that somewhere to be the smallest screen I will develop for.


A mobile phone is not only the smallest, but also the most constraint and possibly even the most used device that people use to browse your website with. Obviously this doesn’t apply to every website in the world but do not underestimate the amount of mobile browsing people do. Because of these factors it makes sense to first perfect the browsing experience on the small screens.

And since it’s also the most constrained browsing experience you will have to focus on the parts of your app that really matter to your users. This will make sure that you don’t just add a lot of noise because it might look cool or pretty.

Development speed

If you’ve made a responsive website before from a desktop first approach you probably noticed that you had to ‘undo’ a lot of your styling and scripting. I’d like to illustrate this with a little bit of code. The code will take an unsorted list and turn it into a nice navigation bar for the desktop view. On mobile the list will be shown as a list.

Do you notice how we first set .nav-list li  to a non-default value, inline-block and then on screens smaller than 600 pixels we set .nav-list li  back to it’s default value. Let’s rewrite this from a mobile-first perspective.

This is a small example so the difference isn’t dramatic but the implications are significant. Instead of adding and removing styles we are simply adding more styles when the screen is at least 600 pixels wide. By taking this approach it’s much more clear what’s going on and it’s also harder to make mistakes.

With the navigation list example in mind, imagine that we want to add a border and some padding to the list items, but only for the desktop view. Let’s compare both approaches again, shall we?

desktop first

mobile first

As you can see the mobile first approach is a lot cleaner. Not only is it cleaner, it’s also safer. We don’t have to worry about resetting certain styles back to their defaults like we have to in our desktop-first approach.

Of course you still have to keep an eye out for cascading accidents because sometimes you set something for mobile that will have to be reset for your desktop view. But in my experience this happens a lot less often with mobile-first than it does with desktop-first.

Adding javascript is easier than removing it

I just showed you that when it comes to css it’s a lot easier to stack on more styles than it is to reset them to defaults for mobile. The same applies for javascript. I usually find myself initializing a lot less (complex) modules for mobile. When you take a mobile-first approach with this you will not initialize certain things at first. Once you know that you’re on a large screen machine you can start initializing your larger, more complex modules that are intended for desktop use.

Not only is it easier to initialize things when you know you need them, it’s also a lot faster. Imagine executing some heavy javascript on a mobile phone only to find out that the module won’t even be used because the target elements are hidden. That’s a waste of precious resources that you might have used to get your page up and running on the device really quick.


In this post I explained to you what a mobile-first approach is from the perspective of a developer. I also showed you how this impacts the process of writing code. Going in mobile-first will prevent you from having to write a lot of ‘reset this to default’ css. It’s also easier for the javascript part of your application. You won’t initialize thing that you don’t need and this generally makes your pages render faster as well.

I’m not saying that a desktop-first approach is worst in every case or scenario, I’m also not saying that the design process has to be mobile first. But thinking about the smallest most constrained devices does seem to result in faster and more focused websites. It also seems to lead to a more solid code base and happier developers.