Mobile First - A Retrospective

Responsive_Web_DesignMost engineers would agree that simply having a mobile-first mindset is not enough to build a high-quality responsive website — we also need relevant mobile-first guidelines and principles. We recently explored the challenges of scaling a mobile-oriented site to tablet and desktop. What we found was not always pretty, but the lessons learned were valuable. In this article, we will explore those lessons, in hopes that we can all improve how we build across mobile, tablet, and desktop.

Building a fully scalable website requires a strong focus on code quality. Concepts such as modularity, encapsulation, and testability become extremely important as you move across domains. Whether we are scaling up to desktop or down to mobile, we need the code to stay consistent and maintainable. Every hacked, poorly planned, or rushed piece of code we might add reduces our ability to write elegant, scalable, responsive code.

Perhaps creating a responsive app is not high on your team’s priority list right now. But one day it will be — and the conversion time frame might be very tight when that day comes.

Ideally, all you need to do is add media query CSS and everything just works. But the only way that can happen is if the code readily adapts to responsive changes.

Below are some suggestions and fixes that will make conversion to responsive easier. Some are specific to responsive design while others are general good practices.

Media queries

Yes, we all know about media queries. How hard can they be? Sprinkle some on any page and you have a responsive website, right?

Using media queries on your pages is essential; they allow you to overwrite CSS values based on screen size. This technique might sound simple, but in a larger project it can quickly get out of hand. A few major problems can get in the way of using media queries properly:

  • Colliding media queries: It is easy to make the mistake of writing media queries that overwrite each other if you do not stick to a common pattern. We recommend using the same boilerplate throughout all projects, and have created one here.
  • Setting element styles from JS: This is a tempting, but inferior, approach to building responsive websites. When an element relies on JS logic to set its width, it is unable to properly use media queries. If the JS logic is setting width as an inline property, the width cannot be overwritten in CSS without using !important. In addition, you have to now maintain an ever-growing set of JS logic.
  • Media queries not at the bottom: If your queries are not loaded last, they will not override their intended targets. Every module might have its own CSS file, and the overall ordering might not place it at the bottom, which leads us to our next point.
  • CSS namespacing for encapsulation: If you are writing a module, its CSS selectors should be properly encapsulated via namespace. We recommend prefixing class names with the module name, such as navbar-parent. Following this pattern will prevent conflicts with other modules, and will ensure that media queries at the bottom of your module’s CSS file override their intended targets.
  • Too many CSS selectors: CSS specificity rules require media queries to use the same specificity in order to override. It is easy to get carried away in LESS, which allows you to nest CSS multiple levels deep. While it can be useful to go one or two levels deep for encapsulation, usually this is unnecessarily complicating your code. We recommend favoring namespacing over nested specifiers as it is cleaner and easier to maintain.
  • Using !important to override styles: Adding !important to your styles reduces maintainability. It is better to avoid relying on !important overrides and instead use CSS namespacing to prevent sharing between modules.

Responsive or adaptive?

Both responsive and adaptive web design techniques contain powerful tools, but it is important to understand the differences between the two. Responsive techniques usually include media queries, fluid grids, and CSS percentage values. Adaptive techniques, on the other hand, are focused more on JavaScript logic, and the adding or removing of features based on device detection or screen size.

So, which should you use? Responsive or adaptive? The answer depends on the feature you are trying to implement. It can be tempting to jump straight into applying adaptive techniques to your feature, but in many cases it may not be required. Worse, applying adaptive techniques can quickly over-complicate your design. An example of this that we saw in many places is the use of JavaScript logic to set CSS style attributes.

Use JavaScript sparingly

When styling your UI, JavaScript should be avoided whenever possible. Dynamic sizing, for example, is better done through media queries. For most UI designs, you will be deciding on layouts based on screen size, not on device type. Confusing the need for device detection with screen size can lead us to apply adaptive where responsive would be superior.

Rethink any design that requires CSS attributes to change based on device detection; in almost all cases it will be better to rely on screen size alone, via media queries. So, when should we use adaptive Javascript techniques?

When to use adaptive

Adaptive web design techniques are powerful, as they allow for selective loading of resources based on user agent or screen size. Logic that checks for desktop browsers, for example, can load high-resolution images instead of their mobile-optimized counterparts. Loading additional resources and features for larger screens can also be useful. Desktop browsers, for example, could show more functionality due to the increased screen size, browser capability, or bandwidth.

Ideally, additional resources will be lazy-loaded for their intended platforms. Lazily loading modules helps with site speed for mobile web, while still allowing for a full set of functionality for desktop and tablet web. This technique can be applied by checking the user agent on the client or server. If done on the server, only resources supported by the user’s platform should be returned. Alternatively, client-based lazy loading can use Ajax requests to load additional resources if they are supported. This effect can be achieved using client-side JavaScript, based on browser support or user agent. Client-side detection is generally preferred, as it allows feature detection based on actual browser functionality instead of potentially complicated user agent checks.

Simple flex grid example

A responsive flex grid doesn’t have to be complicated. In our live demo page, we show a simple implementation that creates a horizontally scrolling section of image containers. The images are centered, allowed to expand up to 100% of their container, and will maintain their original aspect ratio. In addition, the container height values are set to 100%, allowing us to adjust the height in the parent wrapper only, and keeping our media query overrides simple and easy to read.

The html and css source code use the concepts mentioned above. We plan to add more boilerplate patterns; please don’t hesitate to add your own as well. Pull requests are welcomed!

Best practices

We hope that the information above will come in handy when you are working on your next mobile-first web project. Below is a summary of what we mentioned above and other helpful tips.

On using media queries

  • Most responsive layout can and should be done with media queries. JS manipulation of CSS (maybe with the exception of adding/removing classes) should be avoided. Setting width in JS is not as maintainable or dynamic compared to CSS.
  • Use media query boilerplate to ensure you do not have contradicting media queries or have media queries that are always skipped.
  • Put media queries at the bottom. Media queries override CSS and should be the final overrides, whether page level or module level.
  • If your regular CSS rules have many selectors, your media query CSS rules will have to as well, due to CSS specificity rules. Use as few selectors as possible when defining CSS rules.

 On writing CSS

  • Use CSS classes, not CSS IDs, to avoid CSS specificity issues.
  • Use the fewest number of selectors possible to define your selector.
  • Reuse classes. If an element has the same look on different parts of the page, do not create two different classes. Make a generic class and reuse it.
  • Encapsulate your CSS selectors by using proper namespacing to prevent conflicts.

e.g., class=”module-name-parent”

  • It is very rare that you need to use !important. Before you use it, ask yourself whether you can instead add another class (parent or same level). And then ask yourself whether the rule you are trying to override has unnecessary selectors.

 On writing LESS

  • Use LESS nesting only where needed. Nesting is good for organization, but it is also a recipe for CSS specificity issues.
  • Check that you do not have a CSS rule that looks like this:
    #wrapper #body-content #content #left-side #text {
        border: 1px solid #000;
  • Work with the design team and define LESS variables using good names. Then, use these LESS variables everywhere possible.
  • If you are using a set of CSS rules repeatedly, make it a LESS mixin.

 On adding element wrappers

  • Most dom structures are more complex than necessary.
  • Add a wrapper only when needed. Do not add a wrapper when proper CSS can do the same thing.
  • If you remove the wrapper and the layout does not change, you do not need it. Now, do a global search for this wrapper’s references (JS, CSS, rhtml, jsp, tag) and remove them.

On lazy loading

  • Add a placeholder to your component for lazy loading.
  • Lazy-loaded sections will start off empty, so make sure you reserve the correct amount of space for this behavior. Otherwise, you will see the page shift as modules load in.
  • Use media queries for the empty section so that it closely matches the filled size.

On cleaning up

  • If you are playing around with CSS to attempt a layout and it starts working, remember to remove the unnecessary CSS rules. Many of them are probably not needed anymore. Remove the unnecessary wrappers as well.

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