Web-Design
Monday May 24, 2021 By David Quintanilla
Use-Cases And Migration Strategies — Smashing Magazine


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CSS Container queries deliver media queries nearer to the goal components themselves and allows them to adapt to nearly any given container or structure. On this article, we’re going to cowl CSS container question fundamentals and learn how to use them right this moment with progressive enhancement or polyfills.

Once we write media queries for a UI aspect, we at all times describe how that aspect is styled relying on the display screen dimensions. This method works nicely when the responsiveness of the goal aspect media question ought to solely depend upon viewport measurement. Let’s check out the next responsive web page structure instance.

Responsive page layout example. The left image shows the desktop layout at 1280px viewport width and the right image shows the mobile layout at 568px viewport width.
Responsive web page structure instance. The left picture exhibits the desktop structure at 1280px viewport width and the best picture exhibits the cellular structure at 568px viewport width. (Large preview)

Nevertheless, responsive Net Design (RWD) will not be restricted to a web page structure — the person UI elements normally have media queries that may change their fashion relying on the viewport dimensions.

Responsive product card component example. The left image shows a component at 720px viewport width and the right image shows component layout at 568px viewport width.
Responsive product card part instance. The left picture exhibits a part at 720px viewport width and the best picture exhibits part structure at 568px viewport width. (Large preview)

You might need already observed an issue with the earlier assertion — particular person UI part structure typically doesn’t rely solely on the viewport dimensions. Whereas web page structure is a component intently tied to viewport dimensions and is likely one of the topmost components in HTML, UI elements can be utilized in several contexts and containers. If you concentrate on it, the viewport is only a container, and UI elements could be nested inside different containers with types that have an effect on the part’s dimensions and structure.

Example of page layout with the same product card UI component in the top section 3-column grid and the bottom section list.
Instance of web page structure with the identical product card UI part within the high part 3-column grid and the underside part record. (Large preview)

Though the identical product card part is utilized in each the highest and backside sections, part types not solely depend upon the viewport dimensions but in addition depend upon the context and the container CSS properties (just like the grid within the instance) the place it’s positioned.

In fact, we will construction our CSS so we assist the fashion variations for various contexts and containers to deal with the structure challenge manually. Within the worst-case situation, this variation can be added with fashion override which might result in code duplication and specificity points.

.product-card {
    /* Default card fashion */
}

.product-card--narrow {
   /* Fashion variation for slim viewport and containers */
}

@media display screen and (min-width: 569px) {
 .product-card--wide {
     /* Fashion variation for wider viewport and containers */
  }
}

Nevertheless, that is extra of a workaround for the restrictions of media queries reasonably than a correct answer. When writing media queries for UI components we’re looking for a “magic” viewport worth for a breakpoint when the goal aspect has minimal dimensions the place the structure doesn’t break. In brief, we’re linking a “magical” viewport dimension worth to aspect dimensions worth. This worth is normally totally different from than viewport dimension and is susceptible to bugs when interior container dimensions or structure adjustments.

Example of how media query cannot be reliably linked to element dimensions. Various CSS properties can affect element dimensions within a container. In this example, container padding is different between the two images.
Instance of how media question can’t be reliably linked to aspect dimensions. Varied CSS properties can have an effect on aspect dimensions inside a container. On this instance, container padding is totally different between the 2 photographs. (Large preview)

The next instance showcases this precise challenge — though a responsive product card aspect has been applied and it appears to be like good in a normal use-case, it appears to be like damaged if it’s moved to a unique container with CSS properties that have an effect on aspect dimensions. Every further use-case requires further CSS code to be added which might result in duplicated code, code bloat, and code that’s tough to keep up.

See the Pen [Product cards – various containers](https://codepen.io/smashingmag/pen/abJpgvj) by Adrian Bece.

See the Pen Product cards – various containers by Adrian Bece.

This is likely one of the points that container queries making an attempt to repair. Container queries prolong current media queries performance with queries that depend upon the goal aspect dimensions. There are three main advantages of utilizing this method:

  • Container question types are utilized relying on the size of the goal aspect itself. UI elements will be capable of adapt to any given context or container.
  • Builders gained’t must search for a “magic quantity” viewport dimension worth that hyperlinks a viewport media question to a goal dimension of UI part in a selected container or a selected context.
  • No want so as to add further CSS courses or media queries for various contexts and use-cases.

“The perfect responsive web site is a system of versatile, modular elements that may be repurposed to serve in a number of contexts.”

— “Container Queries: Once More Unto the Breach,” Mat Marquis

Earlier than we dive deep into container queries, we have to take a look at the browser assist and see how we will allow the experimental characteristic in our browser.

Browser Help

Container queries are an experimental feature, accessible at present in Chrome Canary model on the time of writing this text. If you wish to comply with alongside and run the CodePen examples on this article you’ll must allow container queries within the following settings URL.

chrome://flags/#enable-container-queries
Container queries
(Large preview)

In case you might be utilizing a browser that doesn’t assist container queries, a picture showcasing the meant working instance might be supplied alongside the CodePen demo.

Working With Container Queries

Container queries aren’t as simple as common media queries. We’ll have so as to add an additional line of CSS code to our UI aspect to make container queries work, however there’s a cause for that and we’ll cowl that subsequent.

Containment Property

CSS include property has been added to nearly all of fashionable browsers and has a good 75% browser support on the time of writing this text. The include property is especially used for efficiency optimization by hinting to the browser which elements (subtrees) of the web page could be handled as impartial and gained’t have an effect on the adjustments to different components in a tree. That manner, if a change happens in a single aspect, the browser will re-render solely that half (subtree) as a substitute of the entire web page. With include property values, we will specify which varieties of containment we need to use — structure, measurement, or paint.

There are a lot of great articles in regards to the include property that define accessible choices and use-cases in far more element, so I’m going to focus solely on properties associated to container queries.

What does the CSS contentment property that’s used for optimization should do with container queries? For container queries to work, the browser must know if a change happens within the aspect’s youngsters structure that it ought to re-render solely that part. The browser will know to use the code within the container question to the matching part when the part is rendered or the part’s dimension adjustments.

We’ll use the structure worth for the include property, however we’ll additionally want an additional value that indicators the browser in regards to the axis during which the change will happen.

  • inline-size
    Containment on the inline axis. It’s anticipated for this worth to have considerably extra use-cases, so it’s being applied first.
  • block-size
    Containment on block axis. It’s nonetheless in growth and isn’t at present accessible.

One minor draw back of the include property is that our structure aspect must be a baby of a include aspect, that means that we’re including an extra nesting stage.

<part>
  <article class="card">
      <div class="card__wrapper">
          <!-- Card content material -->       
      </div>
  </article>
</part>
.card {
   include: structure inline-size;
}

.card__wrapper {
  show: grid;
  grid-gap: 1.5em;
  grid-template-rows: auto auto;
  /* ... */
}

Discover how we aren’t including this worth to a extra distant parent-like part and holding the container as near the affected aspect as attainable.

“Efficiency is the artwork of avoiding work and making any work you do as environment friendly as attainable. In lots of circumstances, it’s about working with the browser, not in opposition to it.”

— “Rendering Performance,” Paul Lewis

That’s the reason we must always appropriately sign the browser in regards to the change. Wrapping a distant dad or mum aspect with a include property could be counter-productive and negatively have an effect on web page efficiency. In worst-case situations of misusing the include property, the structure might even break and the browser gained’t render it appropriately.

Container Question

After the include property has been added to the cardboard aspect wrapper, we will write a container question. We’ve added a include property to a component with card class, so now we will embody any of its youngster components in a container question.

Similar to with common media queries, we have to outline a question utilizing min-width or max-width properties and nest all selectors contained in the block. Nevertheless, we’ll be utilizing the @container key phrase as a substitute of @media to outline a container question.

@container (min-width: 568px) {
  .card__wrapper {
    align-items: middle;
    grid-gap: 1.5em;
    grid-template-rows: auto;
    grid-template-columns: 150px auto;
  }

  .card__image {
    min-width: auto;
    top: auto;
  }
}

Each card__wrapper and card__image aspect are youngsters of card aspect which has the include property outlined. Once we substitute the common media queries with container queries, take away the extra CSS courses for slim containers, and run the CodePen instance in a browser that helps container queries, we get the next consequence.

In this example, we’re not resizing the viewport, but the <section> container element itself that has resize CSS property applied. The component automatically switches between layouts depending on the container dimensions.
On this instance, we’re not resizing the viewport, however the <part> container aspect itself that has resize CSS property utilized. The part robotically switches between layouts relying on the container dimensions. (Large preview)

See the Pen [Product cards – container queries](https://codepen.io/smashingmag/pen/VwpPJmO) by Adrian Bece.

See the Pen Product cards – container queries by Adrian Bece.

Please notice that container queries at present don’t present up in Chrome developer instruments, which makes debugging container queries a bit tough. It’s anticipated that the correct debugging assist might be added to the browser sooner or later.

You possibly can see how container queries enable us to create extra strong and reusable UI elements that may adapt to nearly any container and structure. Nevertheless, correct browser assist for container queries continues to be far-off within the characteristic. Let’s try to see if we will implement container queries utilizing progressive enhancement.

Progressive Enhancement & Polyfills

Let’s see if we will add a fallback to CSS class variation and media queries. We will use CSS feature queries with the @helps rule to detect accessible browser options. Nevertheless, we cannot check for other queries, so we have to add a verify for a include: structure inline-size worth. We’ll should assume that browsers that do assist inline-size property additionally assist container queries.

/* Examine if the inline-size worth is supported */
@helps (include: inline-size) {
  .card {
    include: structure inline-size;
  }
}

/* If the inline-size worth will not be supported, use media question fallback */
@helps not (include: inline-size) {
    @media (min-width: 568px) {
       /* ... */
  }
}

/* Browser ignores @container if it’s not supported */
@container (min-width: 568px) {
  /* Container question types */
}

Nevertheless, this method may result in duplicated types as the identical types are being utilized each by container question and the media question. For those who determine to implement container queries with progressive enhancement, you’d need to use a CSS pre-processor like SASS or a post-processor like PostCSS to keep away from duplicating blocks of code and use CSS mixins or one other method as a substitute.

See the Pen [Product cards – container queries with progressive enhancement](https://codepen.io/smashingmag/pen/MWpJMpr) by Adrian Bece.

See the Pen Product cards – container queries with progressive enhancement by Adrian Bece.

Since this container question spec continues to be in an experimental part, it’s vital to needless to say the spec or implementation is susceptible to alter in future releases.

Alternatively, you need to use polyfills to offer a dependable fallback. There are two JavaScript polyfills I’d like to spotlight, which at present appear to be actively maintained and supply mandatory container question options:

Migrating From Media Queries To Container Queries

For those who determine to implement container queries on an current mission that makes use of media queries, you’ll must refactor HTML and CSS code. I’ve discovered this to be the quickest and most simple manner of including container queries whereas offering a dependable fallback to media queries. Let’s check out the earlier card instance.

<part>
      <div class="card__wrapper card__wrapper--wide">
          <!-- Broad card content material -->       
      </div>
</part>

/* ... */

<apart>
      <div class="card__wrapper">
          <!-- Slender card content material -->        
      </div>
</apart>
.card__wrapper {
  show: grid;
  grid-gap: 1.5em;
  grid-template-rows: auto auto;
  /* ... */
}

.card__image {
  /* ... */
}

@media display screen and (min-width: 568px) {
  .card__wrapper--wide {
    align-items: middle;
    grid-gap: 1.5em;
    grid-template-rows: auto;
    grid-template-columns: 150px auto;
  }

  .card__image {
    /* ... */
  }
}

First, wrap the foundation HTML aspect that has a media question utilized to it with a component that has the include property.

<part>
  <article class="card">
      <div class="card__wrapper">
          <!-- Card content material -->        
      </div>
  </article>
</part>
@helps (include: inline-size) {
  .card {
    include: structure inline-size;
  }
}

Subsequent, wrap a media question in a characteristic question and add a container question.

@helps not (include: inline-size) {
    @media (min-width: 568px) {
    .card__wrapper--wide {
       /* ... */
    }

    .card__image {
       /* ... */
    }
  }
}


@container (min-width: 568px) {
  .card__wrapper {
     /* Similar code as .card__wrapper--wide in media question */
  }

  .card__image {
    /* Similar code as .card__image in media question */
  }
}

Though this technique ends in some code bloat and duplicated code, by utilizing SASS or PostCSS you may keep away from duplicating growth code, so the CSS supply code stays maintainable.

As soon as container queries obtain correct browser assist, you may need to take into account eradicating @helps not (include: inline-size) code blocks and proceed supporting container queries solely.

Stephanie Eckles has lately printed a fantastic article on container queries protecting numerous migration strategies. I like to recommend checking it out for extra data on the subject.

Use-Case Eventualities

As we’ve seen from the earlier examples, container queries are greatest used for extremely reusable elements with a structure that depends upon the accessible container house and that can be utilized in numerous contexts and added to totally different containers on the web page.

Different examples embody (examples require a browser that helps container queries):

Conclusion

As soon as the spec has been applied and broadly supported in browsers, container queries may turn into a game-changing characteristic. It is going to enable builders to jot down queries on part stage, shifting the queries nearer to the associated elements, as a substitute of utilizing the distant and barely-related viewport media queries. This may lead to extra strong, reusable, and maintainable elements that may be capable of adapt to numerous use-cases, layouts, and containers.

Because it stands, container queries are nonetheless in an early, experimental part and the implementation is susceptible to alter. If you wish to begin utilizing container queries in your tasks right this moment, you’ll want so as to add them utilizing progressive enhancement with characteristic detection or use a JavaScript polyfill. Each circumstances will lead to some overhead within the code, so for those who determine to make use of container queries on this early part, make sure that to plan for refactoring the code as soon as the characteristic turns into broadly supported.

References

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