:has – CSS-Tricks https://css-tricks.com Tips, Tricks, and Techniques on using Cascading Style Sheets. Fri, 19 Apr 2024 14:27:55 +0000 en-US hourly 1 https://wordpress.org/?v=6.6.1 https://i0.wp.com/css-tricks.com/wp-content/uploads/2021/07/star.png?fit=32%2C32&ssl=1 :has – CSS-Tricks https://css-tricks.com 32 32 45537868 The Power of :has() in CSS https://css-tricks.com/the-power-of-has-in-css/ https://css-tricks.com/the-power-of-has-in-css/#comments Sat, 30 Mar 2024 02:07:57 +0000 https://css-tricks.com/?p=377635 Hey all you wonderful developers out there! In this post we are going to explore the use of :has() in your next web project. :has() is relatively newish but has gained popularity in the front end community by delivering control …


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Hey all you wonderful developers out there! In this post we are going to explore the use of :has() in your next web project. :has() is relatively newish but has gained popularity in the front end community by delivering control over various elements in your UI. Let’s take a look at what the pseudo class is and how we can utilize it.

Syntax

The :has() CSS pseudo-class helps style an element if any of the things we’re searching for inside it are found and accounted for. It’s like saying, “If there’s something specific inside this box, then style the box this way AND only this way.”

:has(<direct-selector>) {
  /* ... */
}

“The functional :has() CSS pseudo-class represents an element if any of the relative selectors that are passed as an argument match at least one element when anchored against this element. This pseudo-class presents a way of selecting a parent element or a previous sibling element with respect to a reference element by taking a relative selector list as an argument.”

For a more robust explanation, MDN does it perfectly

The Styling Problem

In years past we had no way of styling a parent element based on a direct child of that parent with CSS or an element based on another element. In the chance we had to do that, we would need to use some JavaScript and toggle classes on/off based on the structure of the HTML. :has() solved that problem.


Let’s say that you have a heading level 1 element (h1) that is the title of a post or something of that nature on a blog list page, and then you have a heading level 2 (h2) that directly follows it. This h2 could be a sub-heading for the post. If that h2 is present, important, and directly after the h1, you might want to make that h1 stand out. Before you would have had to write a JS function.

Old School Way – JavaScript

const h1Elements = document.querySelectorAll('h1');

h1Elements.forEach((h1) => {
  const h2Sibling = h1.nextElementSibling;
  if (h2Sibling && h2Sibling.tagName.toLowerCase() === 'h2') {
    h1.classList.add('highlight-content');
  }
});

This JS function is looking for all the h1’s that have a h2 proceeding it, and applying a class of highlight-content to make the h1 stand out as an important article.

New and improved with modern day CSS coming in hot! The capabilities of what we can do in the browser have come a long way. We now can take advantage of CSS to do things that we traditionally would have to do with JavaScript, not everything, but some things.

New School Way – CSS

h1:has(+ h2) {
    color: blue;
}

Throw Some :has() On It!

Now you can use :has() to achieve the same thing that the JS function did. This CSS is checking for any h1 and using the sibling combinator checking for an h2 that immediately follows it, and adds the color of blue to the text. Below are a couple use cases of when :has() can come in handy.

:has Selector Example 1

HTML

<h1>Lorem, ipsum dolor.</h1>
<h2>Lorem ipsum dolor sit amet.</h2>
<p>Lorem, ipsum dolor sit amet consectetur adipisicing elit. Eius, odio voluptatibus est vero iste ad?</p>
	
<!-- WITHOUT HAS BELOW -->

<h1>This is a test</h1>
<p>Lorem, ipsum dolor sit amet consectetur adipisicing elit. Eius, odio voluptatibus est vero iste ad?</p>

CSS

h1:has(+ h2) {
    color: blue;
}
Example of showing :has being used with pseudo classes.

:has Selector Example 2

A lot of times we as workers on the web are manipulating or working with images. We could be using tools that Cloudinary provides to make use of various transformations on our images, but usually we want to add drop shadows, border-radii, and captions (not to be confused with alternative text in an alt attribute).


The example below is using :has() to see if a figure or image has a figcaption element and if it does, it applies some background and a border radius to make the image stand out.

HTML

<section>
  <figure>
    <img src="https://placedog.net/500/280" alt="My aunt sally's dog is a golden retreiver." />
    <figcaption>My Aunt Sally's Doggo</figcaption>
  </figure>
</section>

CSS

figure:has(figcaption) {
  background: #c3baba;
  padding: 0.6rem;
  max-width: 50%;
  border-radius: 5px;
}
Example of :has selector highlighting background an image with an caption vs one that does not.

Can I :has() that?

You can see that :has() has great support across modern browsers.

This browser support data is from Caniuse, which has more detail. A number indicates that browser supports the feature at that version and up.

Desktop

ChromeFirefoxIEEdgeSafari
105121No10515.4

Mobile / Tablet

Android ChromeAndroid FirefoxAndroidiOS Safari
12712712715.4

:has() in the Community!

I reached out to my network on Twitter to see how my peers were using :has() in their day-to-day work and this is what they had to say about it.

“One example I have is styling a specific SVG from a 3rd party package in @saucedopen because I couldn’t style it directly.”

This is what Nick Taylor from OpenSauced had to say about using :has().
svg:has(> #Mail) {
  stroke-width: 1;
}

Lol the last time I used it I was building keyboard functionality into a tree view, so I needed to detect states and classes of sibling elements, but it wasn’t in Firefox yet so I had to find another solution. 🫠

Abbey Perini from Nexcor Food Safety Technologies, Inc.

It is great to see how community members are using modern CSS to solve real world problems, and also a shout out to Abbey using it for accessibility reasons!

Things to Keep in Mind

There are a few key points to keep in mind when using :has() Bullet points referenced from MDN.

  • The pseudo-class takes on specificity of the most specific selector in its argument
  • If the :has() pseudo-class itself is not supported in a browser, the entire selector block will fail unless :has() is in a forgiving selector list, such as in :is() and :where()
  • The :has() pseudo-class cannot be nested within another :has() 
  • Pseudo-elements are also not valid selectors within :has() and pseudo-elements are not valid anchors for :has()

Conclusion

Harnessing the power of CSS, including advanced features like the :has() pseudo-class, empowers us to craft exceptional web experiences. CSS’s strengths lie in its cascade and specificity…the best part, allowing us to leverage its full potential. By embracing the capabilities of CSS, we can drive web design and development forward, unlocking new possibilities and creating groundbreaking user interfaces.

Links:


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More Real-World Uses for :has() https://css-tricks.com/more-real-world-uses-for-has/ https://css-tricks.com/more-real-world-uses-for-has/#comments Fri, 20 Jan 2023 15:34:09 +0000 https://css-tricks.com/?p=376331 The :has() pseudo-class is, hands-down, my favorite new CSS feature. I know it is for many of you as well, at least those of you who took the State of CSS survey. The ability to write selectors upside down …


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The :has() pseudo-class is, hands-down, my favorite new CSS feature. I know it is for many of you as well, at least those of you who took the State of CSS survey. The ability to write selectors upside down gives us more superpowers I’d never thought possible.

I say “more superpowers” because there have already been a ton of really amazing clever ideas published by a bunch of super smart people, like:

This article is not a definitive guide to :has(). It’s also not here to regurgitate what’s already been said. It’s just me (hi 👋) jumping on the bandwagon for a moment to share some of the ways I’m most likely to use :has() in my day-to-day work… that is, once browser support is good enough. (Firefox is the last holdout, but will support it, which is imminent.)

When that does happen, you can bet I’ll start using :has() all over the place. Here are some real-world examples of things I’ve built recently and thought to myself, “Gee, this’ll be so much nicer once :has() is fully supported.”

Avoid having to reach outside your JavaScript component

Have you ever built an interactive component that sometimes needs to affect styles somewhere else on the page? Take the following example, where <nav> is a mega menu, and opening it changes the colors of the <header> content above it.

I feel like I need to do this kind of thing all the time.

This particular example is a React component I made for a site. I had to “reach outside” the React part of the page with document.querySelector(...) and toggle a class on the <body>, <header>, or another component. That’s not the end of the world, but it sure feels a bit yuck. Even in a fully React site (a Next.js site, say), I’d have to choose between managing a menuIsOpen state way higher up the component tree, or do the same DOM element selection — which isn’t very React-y.

With :has(), the problem goes away:

header:has(.megamenu--open) {
  /* style the header differently if it contains 
    an element with the class ".megamenu--open"
  */
}

No more fiddling with other parts of the DOM in my JavaScript components!

Better table striping UX

Adding alternate row “stripes” to your tables can be a nice UX improvement. They help your eyes keep track of which row you’re on as you scan the table.

But in my experience, this doesn’t work great on tables with just two or three rows. If you have, for example, a table with three rows in the <tbody> and you’re “striping” every “even” row, you could end up with just one stripe. That’s not really worth a pattern and might have users wondering what’s so special about that one highlighted row.

Using this technique where Bramus uses :has() to apply styles based on the number of children, we can apply table stripes when there are more than, say, three rows:

What to get fancier? You could also decide to only do this if the table has at least a certain number of columns, too:

table:has(:is(td, th):nth-child(3)) {
  /* only do stuff if there are three or more columns */
}

Remove conditional class logic from templates

I often need to change a page layout depending on what’s on the page. Take the following Grid layout, where the placement of the main content changes grid areas depending on whether there’s a sidebar present.

Layout with left sidebar above a layout with no sidebar.

That’s something that might depend on whether there are sibling pages set in the CMS. I’d normally do this with template logic to conditionally add BEM modifier classes to the layout wrapper to account for both layouts. That CSS might look something like this (responsive rules and other stuff omitted for brevity):

/* m = main content */
/* s = sidebar */
.standard-page--with-sidebar {
  grid-template-areas: 's s s m m m m m m m m m';
}
.standard-page--without-sidebar {
  grid-template-areas: '. m m m m m m m m m . .';
}

CSS-wise, this is totally fine, of course. But it does make the template code a little messy. Depending on your templating language it can get pretty ugly to conditionally add a bunch of classes, especially if you have to do this with lots of child elements too.

Contrast that with a :has()-based approach:

/* m = main content */
/* s = sidebar */
.standard-page:has(.sidebar) {
  grid-template-areas: 's s s m m m m m m m m m';
}
.standard-page:not(:has(.sidebar)) {
  grid-template-areas: '. m m m m m m m m m . .';
}

Honestly, that’s not a whole lot better CSS-wise. But removing the conditional modifier classes from the HTML template is a nice win if you ask me.

It’s easy to think of micro design decisions for :has()like a card when it has an image in it — but I think it’ll be really useful for these macro layout changes too.

Better specificity management

If you read my previous article, you’ll know I’m a stickler for specificity. If, like me, you don’t want your specificity scores blowing out when adding :has() and :not() throughout your styles, be sure to use :where().

That’s because the specificity of :has() is based on the most specific element in its argument list. So, if you have something like an ID in there (why, I’m not sure!), your selector is going to be tough to override in the cascade.

On the other hand, the specificity of :where() is always zero, never adding to the specificity score.

/* specificity score: 0,1,0.
  Same as a .standard-page--with-sidebar 
  modifier class
*/
.standard-page:where(:has(.sidebar)) {
  /* etc */
}

The future’s bright

These are just a few things I can’t wait to be able to use in production. The CSS-Tricks Almanac has a bunch of examples, too. What are you looking forward to doing with :has()? What sort of some real-world examples have you run into where :has() would have been the perfect solution?


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Solved With :has(): Vertical Spacing in Long-Form Text https://css-tricks.com/solved-with-has-vertical-spacing-in-long-form-text/ https://css-tricks.com/solved-with-has-vertical-spacing-in-long-form-text/#comments Wed, 18 Jan 2023 13:44:00 +0000 https://css-tricks.com/?p=376435 If you’ve ever worked on sites with lots of long-form text — especially CMS sites where people can enter screeds of text in a WYSIWYG editor — you’ve likely had to write CSS to manage the vertical spacing between different …


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If you’ve ever worked on sites with lots of long-form text — especially CMS sites where people can enter screeds of text in a WYSIWYG editor — you’ve likely had to write CSS to manage the vertical spacing between different typographic elements, like headings, paragraphs, lists and so on.

It’s surprisingly tricky to get this right. And it’s one reason why things like the Tailwind Typography plugin and Stack Overflow’s Prose exist — although these handle much more than just vertical spacing.

Firefox supports :has() behind the layout.css.has-selector.enabled flag in about:config at the time of writing.

What makes typographic vertical spacing complicated?

Surely it should just be as simple as saying that each element — p, h2, ul, etc. — has some amount of top and/or bottom margin… right? Sadly, this isn’t the case. Consider this desired behavior:

  • The first and last elements in a block of long-form text shouldn’t have any extra space above or below (respectively). This is so that other, non-typographic elements are still placed predictably around the long-form content.
  • Sections within the long-form content should have a nice big space between them. A “section” being a heading and all the following content that belongs to that heading. In practice, this means having a nice big space before a heading… but not if that heading is immediately preceded by another heading!
Example of a Heading 3 following a paragraph and another following a Heading 2.
We want to more space above the Heading 3 when it follows a typographic element, like a paragraph, but less space when it immediately follows another heading.

You need to look no further than right here at CSS-Tricks to see where this could come in handy. Here are a couple of screenshots of spacing I pulled from another article.

A Heading 2 element directly above a Heading 3.
The vertical spacing between Heading 2 and Heading 3
A Heading 3 element directly following a paragraph element.
The vertical space between Heading 3 and a paragraph

The traditional solution

The typical solution I’ve seen involves putting any long-form content in a wrapping div (or a semantic tag, if appropriate). My go-to class name has been .rich-text, which I think I use as a hangover from older versions of the Wagtail CMS, which would add this class automatically when rendering WYSIWYG content. Tailwind Typography uses a .prose class (plus some modifier classes).

Then we add CSS to select all typographic elements in that wrapper and add vertical margins. Noting, of course, the special behavior mentioned above to do with stacked headings and the first/last element.

The traditional solution sounds reasonable… what’s the problem? I think there are a few…

Rigid structure

Having to add a wrapper class like .rich-text in all the right places means baking in a specific structure to your HTML code. That’s sometimes necessary, but it feels like it shouldn’t have to be in this particular case. It can also be easy to forget to do this everywhere you need to, especially if you need to use it for a mix of CMS and hard-coded content.

The HTML structure gets even more rigid when you want to be able to trim the top and bottom margin off the first and last elements, respectively, because they need to be immediate children of the wrapper element, e.g., .rich-text > *:first-child. That > is important — after all, we don’t want to accidentally select the first list item in each ul or ol with this selector.

Mixing margin properties

In the pre-:has() world, we haven’t had a way to select an element based on what follows it. Therefore, the traditional approach to spacing typographic elements involves using a mix of both margin-top and margin-bottom:

  1. We start by setting our default spacing to elements with margin-bottom.
  2. Next, we space out our “sections” using margin-top — i.e. very big space above each heading
  3. Then we override those big margin-tops when a heading is followed immediately by another heading using the adjacent sibling selector (e.g. h2 + h3).

Now, I don’t know about you, but I’ve always felt it’s better to use a single margin direction when spacing things out, generally favoring margin-bottom (that’s assuming the CSS gap property isn’t feasible, which it is not in this case). Whether this is a big deal, or even true, I’ll let you decide. But personally, I’d rather be setting margin-bottom for spacing long-form content.

Collapsing margins

Because of collapsing margins, this mix of top and bottom margins isn’t a big problem per se. Only the larger of two stacked margins will take effect, not the sum of both margins. But… well… I don’t really like collapsing margins.

Collapsing margins are yet one more thing to be aware of. It might be confusing for junior devs who aren’t up to speed with that CSS quirk. The spacing will totally change (i.e. stop collapsing) if you were to change the wrapper to a flex layout with flex-direction: column for instance, which is something that wouldn’t happen if you set your vertical margins in a single direction.

I more-or-less know how collapsing margins work, and I know that they’re there by design. I also know they’ve made my life easier on occasion. But they’ve also made it harder other times. I just think they’re kinda weird, and I’d generally rather avoid relying on them.

The :has() solution

And here is my attempt at solving these issues with :has().

To recap the improvements this aims to make:

  • No wrapper class is required.
  • We’re working with a consistent margin direction.
  • Collapsing margins are avoided (which may or may not be an improvement, depending on your stance).
  • There’s no setting styles and then immediately overriding them.

Notes and caveats on the :has() solution

  • Always check browser support. At time of writing, Firefox only supports :has() behind an experimental flag.
  • My solution doesn’t include all possible typographic elements. For instance, there’s no <blockquote> in my demo. The selector list is easy enough to extend though.
  • My solution also doesn’t handle non-typographic elements that may be present in your particular long-form text blocks, e.g. <img>. That’s because for the sites I work on, we tend to lock down the WYSIWYG as much as possible to core text nodes, like headings, paragraphs, and lists. Anything else — e.g. quotes, images, tables, etc. — is a separate CMS component block, and those blocks themselves are spaced apart from each other when rendered on a page. But again, the selector list can be extended.
  • I’ve only included h1 for the sake of completeness. I usually wouldn’t allow a CMS user to add an h1 via WYSIWYG, as the page title would be baked into the page template somewhere rather than entered in the CMS page editor.
  • I’m not catering for a heading followed immediately by the same level heading (h2 + h2). This would mean that the first heading wouldn’t “own” any content, which seems like a misuse of headings (and, correct me if I’m wrong, but it might violate WCAG 1.3.1 Info and Relationships). I’m also not catering for skipped heading levels, which are invalid.
  • I am in no way knocking the existing approaches I mentioned. If and when I build another Tailwind site I’ll use the excellent Typography plugin, no question!
  • I’m not a designer. I came up with these spacing values by eyeballing it. You probably could (and should) use better values.

Specificity and project structure

I was going to write a whole big thing here about how the traditional method and the new :has() way of doing it might fit into the ITCSS methodology… But now that we have :where() (the zero-specificity selector) you can pretty much choose your preferred level of specificity for any selector now.

That said, the fact that we’re no longer dealing with a wrapper — .prose, .rich-text, etc. — to me makes it feel like this should live in the “elements” layer, i.e. before you start dealing with class-level specificity. I’ve used :where() in my examples to keep specificity consistent. All the selectors in both of my examples have a specificity score of 0,0,1 (except for the bare-bones reset).

Wrapping up

So there you have it, a bleeding-edge solution to a very boring problem! This newer approach is still not what I’d call “simple” CSS — as I said at the beginning, it’s a more complex topic than it might seem at first. But aside from having a few slightly complex selectors, I think the new approach makes more sense overall, and the less rigid HTML structure seems very appealing.

If you end up using this, or something like it, I’d love to know how it works out for you. And if you can think of ways to improve it, I’d love to hear those too!


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:has is an unforgiving selector https://css-tricks.com/has-is-an-unforgiving-selector/ https://css-tricks.com/has-is-an-unforgiving-selector/#comments Wed, 11 Jan 2023 14:18:13 +0000 https://css-tricks.com/?p=376342 A little thing happened on the way to publishing the CSS :has() selector to the ol’ Almanac. I had originally described :has() as a “forgiving” selector, the idea being that anything in its argument is evaluated, even if one or …


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A little thing happened on the way to publishing the CSS :has() selector to the ol’ Almanac. I had originally described :has() as a “forgiving” selector, the idea being that anything in its argument is evaluated, even if one or more of the items is invalid.

/* Example: Do not use! */
article:has(h2, ul, ::-scoobydoo) { }

See ::scoobydoo in there? That’s totally invalid. A forgiving selector list ignores that bogus selector and proceeds to evaluate the rest of the items as if it were written like this:

article:has(h2, ul) { }

:has() was indeed a forgiving selector in a previous draft dated May 7, 2022. But that changed after an issue was reported that the forgiving nature conflicts with jQuery when :has() contains a complex selector (e.g. header h2 + p). The W3C landed on a resolution to make :has() an “unforgiving” selector just a few weeks ago.

So, our previous example? The entire selector list is invalid because the bogus selector is invalid. But the other two forgiving selectors, :is() and :where(), are left unchanged.

There’s a bit of a workaround for this. Remember, :is() and :where()are forgiving, even if :has() is not. That means we can nest either of the those selectors in :has() to get more forgiving behavior:

article:has(:where(h2, ul, ::-scoobydoo)) { }

Which one you use might matter because the specificity of :is() is determined by the most specific item in its list. So, if you need to something less specific you’d do better reaching for :where() since it does not add to the specificity score.

/* Specificity: (0,0,1) */
article:has(:where(h2, ul, ::-scoobydoo)) { }

/* Specificity: (0,0,2) */
article:has(:is(h2, ul, ::-scoobydoo)) { }

We updated a few of our posts to reflect the latest info. I’m seeing plenty of others in the wild that need to be updated, so just a little PSA for anyone who needs to do the same.


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Taming the Cascade With BEM and Modern CSS Selectors https://css-tricks.com/taming-the-cascade-with-bem-and-modern-css-selectors/ https://css-tricks.com/taming-the-cascade-with-bem-and-modern-css-selectors/#comments Mon, 21 Nov 2022 13:59:15 +0000 https://css-tricks.com/?p=375144 BEM. Like seemingly all techniques in the world of front-end development, writing CSS in a BEM format can be polarizing. But it is – at least in my Twitter bubble – one of the better-liked CSS methodologies.

Personally, I think …


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BEM. Like seemingly all techniques in the world of front-end development, writing CSS in a BEM format can be polarizing. But it is – at least in my Twitter bubble – one of the better-liked CSS methodologies.

Personally, I think BEM is good, and I think you should use it. But I also get why you might not.

Regardless of your opinion on BEM, it offers several benefits, the biggest being that it helps avoid specificity clashes in the CSS Cascade. That’s because, if used properly, any selectors written in a BEM format should have the same specificity score (0,1,0). I’ve architected the CSS for plenty of large-scale websites over the years (think government, universities, and banks), and it’s on these larger projects where I’ve found that BEM really shines. Writing CSS is much more fun when you have confidence that the styles you’re writing or editing aren’t affecting some other part of the site.

There are actually exceptions where it is deemed totally acceptable to add specificity. For instance: the :hover and :focus pseudo classes. Those have a specificity score of 0,2,0. Another is pseudo elements — like ::before and ::after — which have a specificity score of 0,1,1. For the rest of this article though, let’s assume we don’t want any other specificity creep. 🤓

But I’m not really here to sell you on BEM. Instead, I want to talk about how we can use it alongside modern CSS selectors — think :is(), :has(), :where(), etc. — to gain even more control of the Cascade.

What’s this about modern CSS selectors?

The CSS Selectors Level 4 spec gives us some powerful new(ish) ways to select elements. Some of my favorites include :is(), :where(), and :not(), each of which is supported by all modern browsers and is safe to use on almost any project nowadays.

:is() and :where() are basically the same thing except for how they impact specificity. Specifically, :where() always has a specificity score of 0,0,0. Yep, even :where(button#widget.some-class) has no specificity. Meanwhile, the specificity of :is() is the element in its argument list with the highest specificity. So, already we have a Cascade-wrangling distinction between two modern selectors that we can work with.

The incredibly powerful :has() relational pseudo-class is also rapidly gaining browser support (and is the biggest new feature of CSS since Grid, in my humble opinion). However, at time of writing, browser support for :has() isn’t quite good enough for use in production just yet.

Lemme stick one of those pseudo-classes in my BEM and…

/* ❌ specificity score: 0,2,0 */
.something:not(.something--special) {
  /* styles for all somethings, except for the special somethings */
}

Whoops! See that specificity score? Remember, with BEM we ideally want our selectors to all have a specificity score of 0,1,0. Why is 0,2,0 bad? Consider a similar example, expanded:

.something:not(a) {
  color: red;
}
.something--special {
  color: blue;
}

Even though the second selector is last in the source order, the first selector’s higher specificity (0,1,1) wins, and the color of .something--special elements will be set to red. That is, assuming your BEM is written properly and the selected element has both the .something base class and .something--special modifier class applied to it in the HTML.

Used carelessly, these pseudo-classes can impact the Cascade in unexpected ways. And it’s these sorts of inconsistencies that can create headaches down the line, especially on larger and more complex codebases.

Dang. So now what?

Remember what I was saying about :where() and the fact that its specificity is zero? We can use that to our advantage:

/* ✅ specificity score: 0,1,0 */
.something:where(:not(.something--special)) {
  /* etc. */
}

The first part of this selector (.something) gets its usual specificity score of 0,1,0. But :where() — and everything inside it — has a specificity of 0, which does not increase the specificity of the selector any further.

:where() allows us to nest

Folks who don’t care as much as me about specificity (and that’s probably a lot of people, to be fair) have had it pretty good when it comes to nesting. With some carefree keyboard strokes, we may wind up with CSS like this (note that I’m using Sass for brevity):

.card { ... }

.card--featured {
  /* etc. */  
  .card__title { ... }
  .card__title { ... }
}

.card__title { ... }
.card__img { ... }

In this example, we have a .card component. When it’s a “featured” card (using the .card--featured class), the card’s title and image needs to be styled differently. But, as we now know, the code above results in a specificity score that is inconsistent with the rest of our system.

A die-hard specificity nerd might have done this instead:

.card { ... }
.card--featured { ... }
.card__title { ... }
.card__title--featured { ... }
.card__img { ... }
.card__img--featured { ... }

That’s not so bad, right? Frankly, this is beautiful CSS.

There is a downside in the HTML though. Seasoned BEM authors are probably painfully aware of the clunky template logic that’s required to conditionally apply modifier classes to multiple elements. In this example, the HTML template needs to conditionally add the --featured modifier class to three elements (.card, .card__title, and .card__img) though probably even more in a real-world example. That’s a lot of if statements.

The :where() selector can help us write a lot less template logic — and fewer BEM classes to boot — without adding to the level of specificity.

.card { ... }
.card--featured { ... }

.card__title { ... }
:where(.card--featured) .card__title { ... }

.card__img { ... }
:where(.card--featured) .card__img { ... }

Here’s same thing but in Sass (note the trailing ampersands):

.card { ... }
.card--featured { ... }
.card__title { 
  /* etc. */ 
  :where(.card--featured) & { ... }
}
.card__img { 
  /* etc. */ 
  :where(.card--featured) & { ... }
}

Whether or not you should opt for this approach over applying modifier classes to the various child elements is a matter of personal preference. But at least :where() gives us the choice now!

What about non-BEM HTML?

We don’t live in a perfect world. Sometimes you need to deal with HTML that is outside of your control. For instance, a third-party script that injects HTML that you need to style. That markup often isn’t written with BEM class names. In some cases those styles don’t use classes at all but IDs!

Once again, :where() has our back. This solution is slightly hacky, as we need to reference the class of an element somewhere further up the DOM tree that we know exists.

/* ❌ specificity score: 1,0,0 */
#widget {
  /* etc. */
}

/* ✅ specificity score: 0,1,0 */
.page-wrapper :where(#widget) {
  /* etc. */
}

Referencing a parent element feels a little risky and restrictive though. What if that parent class changes or isn’t there for some reason? A better (but perhaps equally hacky) solution would be to use :is() instead. Remember, the specificity of :is() is equal to the most specific selector in its selector list.

So, instead of referencing a class we know (or hope!) exists with :where(), as in the above example, we could reference a made up class and the <body> tag.

/* ✅ specificity score: 0,1,0 */
:is(.dummy-class, body) :where(#widget) {
  /* etc. */
}

The ever-present body will help us select our #widget element, and the presence of the .dummy-class class inside the same :is() gives the body selector the same specificity score as a class (0,1,0)… and the use of :where() ensures the selector doesn’t get any more specific than that.

That’s it!

That’s how we can leverage the modern specificity-managing features of the :is() and :where() pseudo-classes alongside the specificity collision prevention that we get when writing CSS in a BEM format. And in the not too distant future, once :has() gains Firefox support (it’s currently supported behind a flag at the time of writing) we’ll likely want to pair it with :where() to undo its specificity.

Whether you go all-in on BEM naming or not, I hope we can agree that having consistency in selector specificity is a good thing!


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Creating Animated, Clickable Cards With the :has() Relational Pseudo Class https://css-tricks.com/creating-animated-clickable-cards-with-the-has-relational-pseudo-class/ https://css-tricks.com/creating-animated-clickable-cards-with-the-has-relational-pseudo-class/#comments Tue, 25 Oct 2022 14:15:17 +0000 https://css-tricks.com/?p=374690 The CSS :has() pseudo class is rolling out in many browsers with Chrome and Safari already fully supporting it. It’s often referred to it as “the parent selector” — as in, we can select style a parent element from a …


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]]>
The CSS :has() pseudo class is rolling out in many browsers with Chrome and Safari already fully supporting it. It’s often referred to it as “the parent selector” — as in, we can select style a parent element from a child selector — but there is so much more that :has() can help us solve. One of those things is re-inventing the clickable card pattern many of us love to use from time to time.

We’ll take a look at how :has() can help us handle linked cards, but first…

What is this :has() pseudo class?

There is already a bunch of great posts floating around that do an excellent job explaining what :has() is and what it’s used for, but it’s still new enough that we ought to say a few words about it here as well.

:has() is a relational pseudo class that’s part of the W3C Selectors Level 4 working draft. That’s what the parentheses are all about: matching elements that are related to — or, more accurately, contain — certain child elements.

/* Matches an article element that contains an image element */
article:has(img) { }

/* Matches an article element with an image contained immediately within it */
article:has(> img) { }

So, you can see why we might want to call it a “parent” selector. But we can also combine it with other functional pseudo classes to get more specific. Say we want to style articles that do not contain any images. We can combine the relational powers of :has() with the negation powers of :not() to do that:

/* Matches an article without images  */
article:not(:has(img)) { }

But that’s just the start of how we can combine powers to do more with :has(). Before we turn specifically to solving the clickable card conundrum, let’s look at a few ways we currently approach them without using :has().

How we currently handle clickable cards

There are three main approaches on how people create a fully clickable card these days and to fully understand the power of this pseudo class, it’s nice to have a bit of a round-up.

This approach is something used quite frequently. I never use this approach but I created a quick demo to demonstrate it:

There are a lot of concerns here, especially when it comes to accessibility. When users navigate your website using the rotor function, they will hear the full text inside of that <a> element — the heading, the text, and the link. Someone might not want to sit through all that. We can do better. Since HTML5, we can nest block elements inside of an <a> element. But it never feels right to me, especially for this reason.

Pros:

  • Quick to implement
  • Semantically correct

Cons:

  • Accessibility concerns
  • Text not selectable
  • A lot of hassle to overwrite styles that you used on your default links

The JavaScript method

Using JavaScript, we can attach a link to our card instead of writing it in the markup. I found this great CodePen demo by costdev who also made the card text selectable in the process:

This approach has a lot of benefits. Our links are accessible on focus and we can even select text. But there are some drawbacks when it comes to styling. If we want to animate those cards, for example, we would have to add :hover styles on our main .card wrapper instead of the link itself. We also would not benefit from the animations when the links are in focus from keyboard tabbing.

Pros:

  • Can be made perfectly accessible
  • Ability to select text

Cons:

  • Requires JavaScript
  • Right clicking not possible (although could be fixed with some extra scripting)
  • Will require a lot of styling on the card itself which would not work when focussing the link

The ::after selector approach

This method requires us to set the card with relative positioning, then set absolute positioning on the link’s ::after pseudo selector of a link. This doesn’t require any JavaScript and is pretty easy to implement:

There are a few drawbacks here, especially when it comes to selecting text. Unless you provide a higher z-index on your card-body, you won’t be able to select text but if you do, be warned that clicking the text will not activate your link. Whether or not you want selectable text is up to you. I think it can be a UX issue, but it depends on the use-case. The text is still accessible to screen readers but my main problem with the method is the lack of animation possibilities.

Pros:

  • Easy to implement
  • Accessible link without bloated text
  • Works on hover and focus

Cons:

  • Text is not selectable
  • You can only animate the link as this is the element you’re hovering.

A new approach: Using ::after with :has()

Now that we’ve established the existing approaches for clickable cards, I want to show how introducing :has() to the mix solves most of those shortcomings.

In fact, let’s base this approach on the last one we looked at using ::after on the link element. We can actually use :has() there to overcome that approach’s animation constraints.

Let’s start with the markup:

<article>
  <figure>
    <img src="cat.webp" alt="Fluffy gray and white tabby kitten snuggled up in a ball." />
  </figure>
  <div clas="article-body">
    <h2>Some Heading</h2>
    <p>Curabitur convallis ac quam vitae laoreet. Nulla mauris ante, euismod sed lacus sit amet, congue bibendum eros. Etiam mattis lobortis porta. Vestibulum ultrices iaculis enim imperdiet egestas.</p>
    <a href="#">
      Read more
       <svg xmlns="http://www.w3.org/2000/svg" class="icon" viewBox="0 0 20 20" fill="currentColor">
         <path fill-rule="evenodd" d="M12.293 5.293a1 1 0 011.414 0l4 4a1 1 0 010 1.414l-4 4a1 1 0 01-1.414-1.414L14.586 11H3a1 1 0 110-2h11.586l-2.293-2.293a1 1 0 010-1.414z" clip-rule="evenodd" />
       </svg>
    </a>
  </div>
</article>

I will be keeping things as simple as possible by targeting elements in the CSS instead of classes.

For this demo, we’re going to add an image zoom and shadow to the card on hover, and animate the link with an arrow popping up and while changing the link’s text color. To make this easy, we’re going to add some custom properties scoped on our card. Here’s the basic styling:

/* The card element */
article {
  --img-scale: 1.001;
  --title-color: black;
  --link-icon-translate: -20px;
  --link-icon-opacity: 0;

  position: relative;
  border-radius: 16px;
  box-shadow: none;
  background: #fff;
  transform-origin: center;
  transition: all 0.4s ease-in-out;
  overflow: hidden;
}
/* The link's ::after pseudo */
article a::after {
  content: "";
  position: absolute;
  inset-block: 0;
  inset-inline: 0;
  cursor: pointer;
}

Great! We added an initial scale for the image (--img-scale: 1.001), the initial color of the card heading (--title-color: black) and some extra properties we will use to make our arrow pop out of the link. We’ve also set an empty state of the box-shadow declaration in order to animate it later . This sets up what we need for the clickable card right now, so let’s add some resets and styling to it by adding those custom properties to the elements we want to animate:

article h2 {
  margin: 0 0 18px 0;
  font-family: "Bebas Neue", cursive;
  font-size: 1.9rem;
  letter-spacing: 0.06em;
  color: var(--title-color);
  transition: color 0.3s ease-out;
}
article figure {
  margin: 0;
  padding: 0;
  aspect-ratio: 16 / 9;
  overflow: hidden;
}
article img {
  max-width: 100%;
  transform-origin: center;
  transform: scale(var(--img-scale));
  transition: transform 0.4s ease-in-out;
}
article a {
  display: inline-flex;
  align-items: center;
  text-decoration: none;
  color: #28666e;
}
article a:focus {
  outline: 1px dotted #28666e;
}
article a .icon {
  min-width: 24px;
  width: 24px;
  height: 24px;
  margin-left: 5px;
  transform: translateX(var(--link-icon-translate));
  opacity: var(--link-icon-opacity);
  transition: all 0.3s;
}

.article-body {
  padding: 24px;
}

Let’s be kind to people and also add a screen reader class hidden behind the link:

.sr-only:not(:focus):not(:active) {
  clip: rect(0 0 0 0); 
  clip-path: inset(50%);
  height: 1px;
  overflow: hidden;
  position: absolute;
  white-space: nowrap; 
  width: 1px;
}

Our card is starting to look pretty sweet. It’s time to add a bit of magic to it. With the :has() pseudo class, we can now check if our link is hovered or focused, then update our custom properties and add a box-shadow. With this little chunk of CSS our card really comes to life:

/* Matches an article element that contains a hover or focus state */
article:has(:hover, :focus) {
  --img-scale: 1.1;
  --title-color: #28666e;
  --link-icon-translate: 0;
  --link-icon-opacity: 1;

  box-shadow: rgba(0, 0, 0, 0.16) 0px 10px 36px 0px, rgba(0, 0, 0, 0.06) 0px 0px 0px 1px;
}

See what’s up there? Now we get the updated styles if any child element in the card is hovered or focused. And even though the link element is the only thing that can contain a hover or focus state in the ::after clickable card approach, we can use that to match the parent element and apply the transitions.

And there you have it. Just another powerful use case for the :has() selector. Not only can we match a parent element by declaring other elements as arguments, but we can match also use pseudos to match and style parents as well.

Pros:

  • Accessible
  • Animatable
  • No JavaScript needed
  • Uses :hover on the correct element

Cons:

  • Text is not easily selectable.
  • Browser support is limited to Chrome and Safari (it’s supported in Firefox behind a flag).

Here is a demo using this technique. You might notice an extra wrapper around the card, but that’s just me playing around with container queries, which is just one of those other fantastic things rolling out in all major browsers.

Got some other examples you wish to share? Other solutions or ideas are more than welcome in the comment section.


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Implicit Grids, Repeatable Layout Patterns, and Danglers https://css-tricks.com/implicit-grids-repeatable-layout-patterns-and-danglers/ https://css-tricks.com/implicit-grids-repeatable-layout-patterns-and-danglers/#comments Tue, 02 Aug 2022 13:10:49 +0000 https://css-tricks.com/?p=367158 Dave Rupert with some modern CSS magic that tackles one of those classic conundrums: what happens when the CSS for component is unable to handle the content we throw at it?

The specific situation is when a layout grid expects …


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Dave Rupert with some modern CSS magic that tackles one of those classic conundrums: what happens when the CSS for component is unable to handle the content we throw at it?

The specific situation is when a layout grid expects an even number of items, but is supplied with an odd number instead. We’re left with a “dangling” element at the end that throws off the layout. Sounds like what’s needed is some Defensive CSS and Dave accomplishes it.

He reaches for :has() to write a nifty selector that sniffs out the last item in a grid that contains an odd number of items:

.items:has(.item:last-of-type:nth-of-type(odd)) .item:first-of-type { }

Breaking that down:

  • We have a parent container of .items.
  • If the container :has() an .item child that is the last of its type,
  • …and that .item happens to be an odd-numbered instance,
  • …then select the first .item element of that type and style it!

In this case, that last .item can be set to go full-width to prevent holes in the layout.

If… then… CSS has conditional logic powers! We’re only talking about support for Safari TP and Edge/Chrome Canary at the moment, but that’s pretty awesome.

As chance has it, Temani Afif recently shared tricks he learned while experimenting with implicit grids. By taking advantage of CSS Grid’s auto-placement algorithm, we don’t even have to explicitly declare a fixed number of columns and rows for a grid — CSS will create them for us if they’re needed!

No, Temani’s techniques aren’t alternative solutions to Dave’s “dangler” dilemma. But combining Temani’s approach to repeatable grid layout patterns with Dave’s defensive CSS use of :has(), we get a pretty powerful and complex-looking grid that’s lightweight and capable of handling any number of items while maintaining a balanced, repeatable pattern.


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Meet `:has`, A Native CSS Parent Selector https://css-tricks.com/meet-has-a-native-css-parent-selector/ https://css-tricks.com/meet-has-a-native-css-parent-selector/#comments Mon, 12 Jul 2021 19:45:00 +0000 https://css-tricks.com/?p=344355 The reasons that are often cited that make container queries difficult or impossible is things like infinite loops—e.g. changing the width of an element, invalidating a container query, which changes the width again, which makes the container query take effect, …


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The reasons that are often cited that make container queries difficult or impossible is things like infinite loops—e.g. changing the width of an element, invalidating a container query, which changes the width again, which makes the container query take effect, etc. But that was solved with containment. A “parent selector”, or :has as it is now been officially dubbed (I like it, that’s how jQuery rolled, although Adrian pointed out a tweet noting that it’s more versatile), has traditionally had similar problems. Things like requiring “multiple pass” rendering which is too slow to be acceptable.

Brian Kardell says:

Primarily, even without :has() it’s pretty hard to live up to performance guarantees of CSS, where everything continue to evaluate and render “live” at 60fps. If you think, mathematically, about just how much work is conceptually involved in applying hundreds or thousands of rules as the DOM changes (including as it is parsing), it’s quite a feat as is.

Engines have figured out how to optimize this based on clever patterns and observations that avoid the work that is conceptually necessary – and a lot of that is sort of based on these subject invariants that has() would appear to throw to the wind.

The fact that there is a spec now is super encouraging, and that it has Igalia’s eye on it. Apparently, some of the performance problems have either been surmounted or, through testing, determined to be negligible enough to remain a shippable feature.

Adrian Bece digs into it all!

The team at Igalia has worked on some notable web engine features like CSS grid and container queries, so there is a chance for :has selector to see the light of day, but there is still a long way to go.

What makes relational selector one of the most requested features in the past few years and how are the developers working around the missing selector? In this article, we’re going to answer those questions and check out the early spec of :has selector and see how it should improve the styling workflow once it’s released.

Let’s cross our fingers. I’ve been watching this for 10 years and trying to document use cases.

To Shared LinkPermalink on CSS-Tricks


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Can I :has() https://css-tricks.com/can-i-has/ https://css-tricks.com/can-i-has/#respond Fri, 04 Jun 2021 14:37:59 +0000 https://css-tricks.com/?p=341968 I just joked that we’re basically getting everything we want in CSS super fast (mostly referring to container queries, my gosh, can you imagine they are actually coming?). Now we might actually get parent selectors?! As in .parent:has(.child) {


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I just joked that we’re basically getting everything we want in CSS super fast (mostly referring to container queries, my gosh, can you imagine they are actually coming?). Now we might actually get parent selectors?! As in .parent:has(.child) { }. Traditionally it’s been nope, too slow, browsers can’t do it. Brian Kardell:

Igalia engineers have been looking into this problem. We’ve been having discussions with Chromium developers, looking into Firefox and WebKit codebases and doing some initial protypes and tests to really get our heads around it. Through this, we’ve provided lots of data about performance of what we have already and where we believe challenges and possibilities lie. We’ve begun sketching out an explainer with all of our design notes and questions linked up

Like I said in 2010: Want!

Here’s some other use cases in the blog post and comment section.

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The CSS :has Selector (and 4+ Examples) https://css-tricks.com/the-css-has-selector/ https://css-tricks.com/the-css-has-selector/#comments Wed, 17 Mar 2021 18:40:16 +0000 https://css-tricks.com/?p=336424 The CSS :has selector helps you select elements when they contain other elements that match the selector you pass into :has().


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The CSS :has selector helps you select elements that contain elements that match the selector you pass into the :has() function. It’s essentially a “parent” selector, although far more useful than just that. For example, imagine being able to select all <div>s but only when they contain a <p>. That’s what we can do:

div:has(p) {
  background: red;
}
/*
  <div> <!-- selected! -->
     <p></p>
  <div>

  <div></div> <!-- not selected -->
  <div> <!-- not selected -->
    <section></section>
  </div>
*/

Although it’s not supported in any browser as I write, it has now dropped in Safari Technical Preview 137, so it’s starting to happen!

Pretty darn handy right! Here’s another example. Say you want space after your headers. Of course! A bit of margin-block-end on your h2 should do it. But… what if there is a subtitle? Now we can select a parent on the condition a subtitle is present and adjust the spacing.

h2,
.subtitle {
  margin: 0 0 1.5rem 0;
}
.header-group:has(h2):has(.subtitle) h2 {
  margin: 0 0 0.2rem 0; /* reduce spacing on header, because subtitle will handle it */
}

/*
  <div class="header-group">
    <h2>Blog Post Title</h2> <!-- main spacing applied here -->
  </div>

  <div class="header-group">
    <h2>Blog Post Title</h2>
    <div class="subtitle"> <!-- main spacing applied here -->
      This is a subtitle
    </div>
  </div>
*/
The CSS :has selector being helpful in spacing headers with subtitles (or not).
On the left, the main spacing happens after the h2, on the right, the main spacing happens after the subtitle.

The way I think about :has is this: it’s a parent selector pseudo-class. That is CSS-speak for “it lets you change the parent element if it has a child or another element that follows it.” This might feel weird! It might break your mental model of how CSS works. This is how I’m used to thinking about CSS:

.parent .child {
  color: red;
}

You can only style down, from parent to child, but never back up the tree. :has completely changes this because up until now there have been no parent selectors in CSS and there are some good reasons why. Because of the way in which browsers parse HTML and CSS, selecting the parent if certain conditions are met could lead to all sorts of performance concerns.

If I sit down and think about all the ways I might use :has today, I sort of get a headache. It would open up this pandora’s box of opportunities that have never been possible with CSS alone.

Another example: let’s say we want to only apply styles to links that have images in them:

a:has(> img) {
  border: 20px solid white;
}

This would be helpful from time to time. I can also see :has being used for conditionally adding margin and padding to elements depending on their content. That would be neat.

The :has selector is part of the CSS Selectors Level 4 specification which is the same spec that has the extremely useful :not pseudo-class.


You could argue that the CSS :has selector is more powerful than just a “parent” selector, which is exactly what Bramus has done! Like in the subheadings example above, you aren’t necessarily ultimately selecting the parent, you might select the parent in a has-condition, but then ultimately select a child element from there.

/*  Matches <figure> elements that have a <figcaption> as a child element */
figure:has(figcaption) { … }

/* Matches <img> elements that is a child of a <figure> that contains a <figcaption> child element */
figure:has(figcaption) img { … }

There you can quickly see that the second selector is selecting a child <img>, not just the parent of the <figcaption>.

Selector List

You can chain it:

article:has(h2):has(ul) {

}

Or give it a selector list:

article:has(h2, ul) {

}

And the list is forgiving: The list is no longer “forgiving” after the W3C adopted a resolution in December 2020 in response to a reported issue. So, if the selector list contains even one invalid argument, the entire list is ignored:

/* 👎 */
article:has(h2, ul, ::-blahdeath) {
  /* ::blahdeath is invalid, making the entire selector invalid. */
}

A workaround is to nest a more forgiving selector in there, such as :is() or :where():

/* 👍 */
article:has(:where(h2, ul, ::-blahdeath)) {
  /* :where is a forgiving selector, making this valid. */
}

Testing for Support

@supports(selector(:has(p))) {
  /* Supported! */
}

The :not() selector is part of the same spec…

Unlike :has, :not does have pretty decent browser support and I used it for the first time the other day:

ul li:not(:first-of-type) {
  color: red;
}

That’s great I also love how gosh darn readable it is; you don’t ever have to have seen this line of code to understand what it does.

Another way you can use :not is for margins:

ul li:not(:last-of-type) {
  margin-bottom: 20px;
}

So every element that is not the last item gets a margin. This is useful if you have a bunch of elements in a card, like this:

… and also :is() and :where()

CSS Selectors Level 4 is also the same spec that has the :is selector that can be used like this today in a lot of browsers:

:is(section, article, aside, nav) :is(h1, h2, h3, h4, h5, h6) {
  color: #BADA55;
}

/* ... which would be the equivalent of: */
section h1, section h2, section h3, section h4, section h5, section h6, 
article h1, article h2, article h3, article h4, article h5, article h6, 
aside h1, aside h2, aside h3, aside h4, aside h5, aside h6, 
nav h1, nav h2, nav h3, nav h4, nav h5, nav h6 {
  color: #BADA55;
}

More Info

So that’s it! :has should be quite useful to use soon, and its cousins :is and :not can be fabulously helpful already and that’s only a tiny glimpse — just three CSS pseudo-classes — that are available in this new spec.


The CSS :has Selector (and 4+ Examples) originally published on CSS-Tricks, which is part of the DigitalOcean family. You should get the newsletter.

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