Is It Time for a Rethink? – A Record Aside

The mobile-first design methodology is nice—it focuses on what actually issues to the person, it’s well-practiced, and it’s been a standard design sample for years. So growing your CSS mobile-first also needs to be nice, too…proper? 

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Properly, not essentially. Traditional mobile-first CSS improvement is predicated on the precept of overwriting fashion declarations: you start your CSS with default fashion declarations, and overwrite and/or add new kinds as you add breakpoints with min-width media queries for bigger viewports (for a great overview see “What’s Cell First CSS and Why Does It Rock?”). However all these exceptions create complexity and inefficiency, which in flip can result in an elevated testing effort and a code base that’s more durable to keep up. Admit it—how many people willingly need that?

By yourself tasks, mobile-first CSS could but be the perfect instrument for the job, however first it is advisable consider simply how applicable it’s in mild of the visible design and person interactions you’re engaged on. That can assist you get began, right here’s how I am going about tackling the components it is advisable look ahead to, and I’ll talk about some alternate options if mobile-first doesn’t appear to fit your undertaking.

Benefits of mobile-first#section2

Among the issues to love with mobile-first CSS improvement—and why it’s been the de facto improvement methodology for thus lengthy—make loads of sense:

Growth hierarchy. One factor you undoubtedly get from mobile-first is a pleasant improvement hierarchy—you simply give attention to the cellular view and get growing. 

Tried and examined. It’s a tried and examined methodology that’s labored for years for a motive: it solves an issue very well.

Prioritizes the cellular view. The cellular view is the easiest and arguably crucial, because it encompasses all the important thing person journeys, and sometimes accounts for a larger proportion of person visits (relying on the undertaking). 

Prevents desktop-centric improvement. As improvement is completed utilizing desktop computer systems, it may be tempting to initially give attention to the desktop view. However fascinated about cellular from the beginning prevents us from getting caught in a while; nobody needs to spend their time retrofitting a desktop-centric web site to work on cellular gadgets!

Disadvantages of mobile-first#section3

Setting fashion declarations after which overwriting them at larger breakpoints can result in undesirable ramifications:

Extra complexity. The farther up the breakpoint hierarchy you go, the extra pointless code you inherit from decrease breakpoints. 

Greater CSS specificity. Kinds which were reverted to their browser default worth in a category title declaration now have a better specificity. This generally is a headache on massive tasks if you wish to maintain the CSS selectors so simple as doable.

Requires extra regression testing. Adjustments to the CSS at a decrease view (like including a brand new fashion) requires all larger breakpoints to be regression examined.

The browser can’t prioritize CSS downloads. At wider breakpoints, basic mobile-first min-width media queries don’t leverage the browser’s functionality to obtain CSS information in precedence order.

The issue of property worth overrides#section4

There may be nothing inherently fallacious with overwriting values; CSS was designed to do exactly that. Nonetheless, inheriting incorrect values is unhelpful and will be burdensome and inefficient. It could additionally result in elevated fashion specificity when it’s a must to overwrite kinds to reset them again to their defaults, one thing which will trigger points in a while, particularly in case you are utilizing a mixture of bespoke CSS and utility courses. We gained’t have the ability to use a utility class for a method that has been reset with a better specificity.

With this in thoughts, I’m growing CSS with a give attention to the default values way more nowadays. Since there’s no particular order, and no chains of particular values to maintain observe of, this frees me to develop breakpoints concurrently. I consider discovering widespread kinds and isolating the precise exceptions in closed media question ranges (that’s, any vary with a max-width set). 

This method opens up some alternatives, as you’ll be able to have a look at every breakpoint as a clear slate. If a element’s format seems to be prefer it needs to be based mostly on Flexbox in any respect breakpoints, it’s superb and will be coded within the default fashion sheet. But when it seems to be like Grid can be significantly better for giant screens and Flexbox for cellular, these can each be carried out totally independently when the CSS is put into closed media question ranges. Additionally, growing concurrently requires you to have a great understanding of any given element in all breakpoints up entrance. This may also help floor points within the design earlier within the improvement course of. We don’t wish to get caught down a rabbit gap constructing a fancy element for cellular, after which get the designs for desktop and discover they’re equally complicated and incompatible with the HTML we created for the cellular view! 

Although this method isn’t going to swimsuit everybody, I encourage you to present it a attempt. There are many instruments on the market to assist with concurrent improvement, resembling Responsively App, Blisk, and lots of others. 

Having mentioned that, I don’t really feel the order itself is especially related. In case you are snug with specializing in the cellular view, have a great understanding of the necessities for different breakpoints, and like to work on one gadget at a time, then by all means keep on with the basic improvement order. The necessary factor is to determine widespread kinds and exceptions so you’ll be able to put them within the related stylesheet—a form of guide tree-shaking course of! Personally, I discover this a bit simpler when engaged on a element throughout breakpoints, however that’s not at all a requirement.

Closed media question ranges in observe #section5

In basic mobile-first CSS we overwrite the kinds, however we will keep away from this by utilizing media question ranges. As an instance the distinction (I’m utilizing SCSS for brevity), let’s assume there are three visible designs: 

  • smaller than 768
  • from 768 to under 1024
  • 1024 and something bigger 

Take a easy instance the place a block-level component has a default padding of “20px,” which is overwritten at pill to be “40px” and set again to “20px” on desktop.

Traditional min-width mobile-first

.my-block {
  padding: 20px;
  @media (min-width: 768px) {
    padding: 40px;
  @media (min-width: 1024px) {
    padding: 20px;

Closed media question vary

.my-block {
  padding: 20px;
  @media (min-width: 768px) and (max-width: 1023.98px) {
    padding: 40px;

The refined distinction is that the mobile-first instance units the default padding to “20px” after which overwrites it at every breakpoint, setting it thrice in complete. In distinction, the second instance units the default padding to “20px” and solely overrides it on the related breakpoint the place it isn’t the default worth (on this occasion, pill is the exception).

The purpose is to: 

  • Solely set kinds when wanted. 
  • Not set them with the expectation of overwriting them in a while, time and again. 

To this finish, closed media question ranges are our greatest pal. If we have to make a change to any given view, we make it within the CSS media question vary that applies to the precise breakpoint. We’ll be a lot much less more likely to introduce undesirable alterations, and our regression testing solely must give attention to the breakpoint we’ve really edited. 

Taking the above instance, if we discover that .my-block spacing on desktop is already accounted for by the margin at that breakpoint, and since we wish to take away the padding altogether, we might do that by setting the cellular padding in a closed media question vary.

.my-block {
  @media (max-width: 767.98px) {
    padding: 20px;
  @media (min-width: 768px) and (max-width: 1023.98px) {
    padding: 40px;

The browser default padding for our block is “0,” so as a substitute of including a desktop media question and utilizing unset or “0” for the padding worth (which we would wish with mobile-first), we will wrap the cellular padding in a closed media question (since it’s now additionally an exception) so it gained’t get picked up at wider breakpoints. On the desktop breakpoint, we gained’t must set any padding fashion, as we would like the browser default worth.

Bundling versus separating the CSS#section6

Again within the day, conserving the variety of requests to a minimal was crucial as a result of browser’s restrict of concurrent requests (usually round six). As a consequence, using picture sprites and CSS bundling was the norm, with all of the CSS being downloaded in a single go, as one stylesheet with highest precedence. 

With HTTP/2 and HTTP/3 now on the scene, the variety of requests is not the massive deal it was. This permits us to separate the CSS into a number of information by media question. The clear advantage of that is the browser can now request the CSS it at the moment wants with a better precedence than the CSS it doesn’t. That is extra performant and might cut back the general time web page rendering is blocked.

Which HTTP model are you utilizing?#section7

To find out which model of HTTP you’re utilizing, go to your web site and open your browser’s dev instruments. Subsequent, choose the Community tab and ensure the Protocol column is seen. If “h2” is listed underneath Protocol, it means HTTP/2 is getting used. 

Be aware: to view the Protocol in your browser’s dev instruments, go to the Community tab, reload your web page, right-click any column header (e.g., Title), and examine the Protocol column.

Chrome dev tools, Network tab filtered by document, Protocol column
Be aware: for a summarized comparability, see ImageKit’s “HTTP/2 vs. HTTP/1.”

Additionally, in case your web site continues to be utilizing HTTP/1…WHY?!! What are you ready for? There may be wonderful person help for HTTP/2.

Separating the CSS into particular person information is a worthwhile job. Linking the separate CSS information utilizing the related media attribute permits the browser to determine which information are wanted instantly (as a result of they’re render-blocking) and which will be deferred. Primarily based on this, it allocates every file an applicable precedence.

Within the following instance of a web site visited on a cellular breakpoint, we will see the cellular and default CSS are loaded with “Highest” precedence, as they’re at the moment wanted to render the web page. The remaining CSS information (print, pill, and desktop) are nonetheless downloaded in case they’ll be wanted later, however with “Lowest” precedence. 

Chrome dev tools, Network tab filtered by css, Priority column

With bundled CSS, the browser must obtain the CSS file and parse it earlier than rendering can begin.

Whereas, as famous, with the CSS separated into completely different information linked and marked up with the related media attribute, the browser can prioritize the information it at the moment wants. Utilizing closed media question ranges permits the browser to do that in any respect widths, versus basic mobile-first min-width queries, the place the desktop browser must obtain all of the CSS with Highest precedence. We are able to’t assume that desktop customers at all times have a quick connection. For example, in lots of rural areas, web connection speeds are nonetheless gradual. 

The media queries and variety of separate CSS information will differ from undertaking to undertaking based mostly on undertaking necessities, however would possibly look just like the instance under.

Bundled CSS

<hyperlink href=" site.css" rel="stylesheet">

This single file incorporates all of the CSS, together with all media queries, and will probably be downloaded with Highest precedence.

Separated CSS

<hyperlink href="" rel="stylesheet"><hyperlink href="cellular.css" media="display screen and (max-width: 767.98px)" rel="stylesheet"><hyperlink href="pill.css" media="display screen and (min-width: 768px) and (max-width: 1083.98px)" rel="stylesheet"><hyperlink href="desktop.css" media="display screen and (min-width: 1084px)" rel="stylesheet"><hyperlink href="print.css" media="print" rel="stylesheet">

Separating the CSS and specifying a media attribute worth on every hyperlink tag permits the browser to prioritize what it at the moment wants. Out of the 5 information listed above, two might be downloaded with Highest precedence: the default file, and the file that matches the present media question. The others might be downloaded with Lowest precedence.

Relying on the undertaking’s deployment technique, a change to at least one file (cellular.css, for instance) would solely require the QA crew to regression check on gadgets in that particular media question vary. Evaluate that to the prospect of deploying the one bundled web site.css file, an method that will usually set off a full regression check.

The uptake of mobile-first CSS was a extremely necessary milestone in internet improvement; it has helped front-end builders give attention to cellular internet purposes, fairly than growing websites on desktop after which making an attempt to retrofit them to work on different gadgets.

I don’t assume anybody needs to return to that improvement mannequin once more, however it’s necessary we don’t lose sight of the difficulty it highlighted: that issues can simply get convoluted and fewer environment friendly if we prioritize one explicit gadget—any gadget—over others. For that reason, specializing in the CSS in its personal proper, at all times conscious of what’s the default setting and what’s an exception, looks as if the pure subsequent step. I’ve began noticing small simplifications in my very own CSS, in addition to different builders’, and that testing and upkeep work can be a bit extra simplified and productive. 

Basically, simplifying CSS rule creation at any time when we will is finally a cleaner method than going round in circles of overrides. However whichever methodology you select, it must swimsuit the undertaking. Cell-first could—or could not—develop into the only option for what’s concerned, however first it is advisable solidly perceive the trade-offs you’re entering into.

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