Tags: aria

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Thursday, April 18th, 2019

Inlining SVG background images in CSS with custom properties

Here’s a tiny lesson that I picked up from Trys that I’d like to share with you…

I was working on some upcoming changes to the Clearleft site recently. One particular component needed some SVG background images. I decided I’d inline the SVGs in the CSS to avoid extra network requests. It’s pretty straightforward:

.myComponent {
    background-image: url('data:image/svg+xml;utf8,<svg> ... </svg>');
}

You can basically paste your SVG in there, although you need to a little bit of URL encoding: I found that converting # to %23 to was enough for my needs.

But here’s the thing. My component had some variations. One of the variations had multiple background images. There was a second background image in addition to the first. There’s no way in CSS to add an additional background image without writing a whole background-image declaration:

.myComponent--variant {
    background-image: url('data:image/svg+xml;utf8,<svg> ... </svg>'), url('data:image/svg+xml;utf8,<svg> ... </svg>');
}

So now I’ve got the same SVG source inlined in two places. That negates any performance benefits I was getting from inlining in the first place.

That’s where Trys comes in. He shared a nifty technique he uses in this exact situation: put the SVG source into a custom property!

:root {
    --firstSVG: url('data:image/svg+xml;utf8,<svg> ... </svg>');
    --secondSVG: url('data:image/svg+xml;utf8,<svg> ... </svg>');
}

Then you can reference those in your background-image declarations:

.myComponent {
    background-image: var(--firstSVG);
}
.myComponent--variant {
    background-image: var(--firstSVG), var(--secondSVG);
}

Brilliant! Not only does this remove any duplication of the SVG source, it also makes your CSS nice and readable: no more big blobs of SVG source code in the middle of your style sheet.

You might be wondering what will happen in older browsers that don’t support CSS custom properties (that would be Internet Explorer 11). Those browsers won’t get any background image. Which is fine. It’s a background image. Therefore it’s decoration. If it were an important image, it wouldn’t be in the background.

Progressive enhancement, innit?

Wednesday, March 20th, 2019

CSS custom properties in generated content

Cassie posted a neat tiny lesson that she’s written a reduced test case for.

Here’s the situation…

CSS custom properties are fantastic. You can drop them in just about anywhere that a property takes a value.

Here’s an example of defining a custom property for a length:

:root {
    --my-value: 1em;
}

Then I can use that anywhere I’d normally give something a length:

.my-element {
    margin-bottom: var(--my-value);
}

I went a bit overboard with custom properties on the new Patterns Day site. I used them for colour values, font stacks, and spacing. Design tokens, I guess. They really come into their own when you combine them with media queries: you can update the values of the custom properties based on screen size …without having to redefine where those properties are applied. Also, they can be updated via JavaScript so they make for a great common language between CSS and JavaScript: you can define where they’re used in your CSS and then update their values in JavaScript, perhaps in response to user interaction.

But there are a few places where you can’t use custom properties. You can’t, for example, use them as part of a media query. This won’t work:

@media all and (min-width: var(--my-value)) {
    ...
}

You also can’t use them in generated content if the value is a number. This won’t work:

:root {
    --number-value: 15;
}
.my-element::before {
    content: var(--number-value);
}

Fair enough. Generated content in CSS is kind of a strange beast. Eric delivered an entire hour-long talk at An Event Apart in Seattle on generated content.

But Cassie found a workaround if the value you want to put into that content property is numeric. The CSS counter value is a kind of generated content—the numbers that appear in front of ordered list items. And you can control the value of those numbers from CSS.

CSS counters work kind of like variables. You name them and assign values to them using the counter-reset property:

.my-element {
    counter-reset: mycounter 15;
}

You can then reference the value of mycounter in a content property using the counter value:

.my-element {
    content: counter(mycounter);
}

Cassie realised that even though you can’t pass in a custom property directly to generated content, you can pass in a custom property to the counter-reset property. So you can do this:

:root {
    --number-value: 15;
}
.my-element {
    counter-reset: mycounter var(--number-value);
    content: counter(mycounter);
}

In a roundabout way, this allows you to use a custom property for generated content!

I realise that the use cases are pretty narrow, but I can’t help but be impressed with the thinking behind this. Personally, I would’ve just read that generated content doesn’t accept custom properties and moved on. I would’ve given up quickly. But Cassie took a step back and found a creative pass-the-parcel solution to the problem.

I feel like this is a hack in the best sense of the word: a creatively improvised solution to a problem or limitation.

I was trying to display the numeric value stored in a CSS variable inside generated content… Turns out you can’t do that. But you can do this… codepen.io/cassie-codes/p… (not saying you should, but you could)

Wednesday, March 13th, 2019

The web we broke. — Ethan Marcotte

Like Eric, Ethan is feeling rightly glum about the state of accessibility on the web. But…

Right now, I’m trying to focus on this one question:

What’s one thing I wish I understood better about accessibility?

Fighting uphill | Eric Bailey

Eric is down about the current dismal state of accessibility on the web. Understandably so. It’s particularly worrying that the problem might be embedded into hiring practices:

Overwhelmingly, crushingly, we shove new developers towards learning JavaScript single page application frameworks (SPAs). While many of these frameworks pay lip service towards preserving accessibility, if you do your homework you find that the majority of them were built without assistive technology in mind.

But it’s not all doom and gloom. Eric also points to initiatives that could really help.

Still, this is a tough question to ask out loud:

What if we’re losing?

Monday, February 25th, 2019

Accessibility on The Session

I spent some time this weekend working on an accessibility issue over on The Session. Someone using VoiceOver on iOS was having a hard time with some multi-step forms.

These forms have been enhanced with some Ajax to add some motion design: instead of refreshing the whole page, the next form is grabbed from the server while the previous one swooshes off the screen.

You can see similar functionality—without the animation—wherever there’s pagination on the site.

The pagination is using Ajax to enhance regular prev/next links—here’s the code.

The multi-step forms are using Ajax to enhance regular form submissions—here’s the code for that.

Both of those are using a wrapper I wrote for XMLHttpRequest.

That wrapper also adds some ARIA attributes. The region of the page that will be updated gets an aria-live value of polite. Then, whenever new content is being injected, the same region gets an aria-busy value of true. Once the update is done, the aria-busy value gets changed back to false.

That all seems to work fine, but I was also giving the same region of the page an aria-atomic value of true. My thinking was that, because the whole region was going to be updated with new content from the server, it was safe to treat it as one self-contained unit. But it looks like this is what was causing the problem, especially when I was also adding and removing class values on the region in order to trigger animations. VoiceOver seemed to be getting a bit confused and overly verbose.

I’ve removed the aria-atomic attribute now. True to its name, I’m guessing it’s better suited to small areas of a document rather than big chunks. (If anyone has a good primer on when to use and when to avoid aria-atomic, I’m all ears).

I was glad I was able to find a fix—hopefully one that doesn’t negatively impact the experience in other screen readers. As is so often the case, the issue was with me trying to be too clever with ARIA, and the solution was to ease up on adding so many ARIA attributes.

It also led to a nice discussion with some of the screen-reader users on The Session.

For me, all of this really highlights the beauty of the web, when everyone is able to contribute to a community like The Session, regardless of what kind of software they may be using. In the tunes section, that’s really helped by the use of ABC notation, as I wrote five years ago:

One of those screen-reader users got in touch with me shortly after joining to ask me to explain what ABC was all about. I pointed them at some explanatory links. Once the format “clicked” with them, they got quite enthused. They pointed out that if the sheet music were only available as an image, it would mean very little to them. But by providing the ABC notation alongside the sheet music, they could read the music note-for-note.

That’s when it struck me that ABC notation is effectively alt text for sheet music!

Then, for those of use who can read sheet music, the text of the ABC notation is automatically turned into an SVG image using the brilliant abcjs. It’s like an enhancement that’s applied, I dunno, what’s the word …progressively.

Tuesday, February 5th, 2019

Revisiting the abbr element

Ire takes a deep dive into implementing an accessible tool tip.

Sunday, January 27th, 2019

Make Your ARIA Labels Sing on Key — Knowbility

A good look at the (over)use of the aria-label attribute that confirms the first rule of ARIA.

Friday, January 11th, 2019

Stepping away from Sass

I think Cathy might’ve buried the lede:

The knock on effect of this was removing media queries. As I moved towards some of the more modern features of CSS the need to target specific screen sizes with unique code was removed.

But on the topic of Sass, layout is now taken care of with CSS grid, variables are taken care of with CSS custom properties, and mixins for typography are taken care of with calc().

Personally, I’ve always found the most useful feature of Sass to simply be that you can have lots of separate Sass files that get combined into one CSS file—very handy for component libraries.

Saturday, December 15th, 2018

Using aria-live

A terrific explanation of the aria-live attribute from Ire. If you’re doing anything with Ajax, this is vital knowledge.

Saturday, November 17th, 2018

Difference between currentColor & Custom Properties | Mike Riethmuller

I had to read through this twice, but I think I get it now (I’m not the sharpest knife in the drawer). Very useful if you’re doing theming in CSS.

Saturday, October 6th, 2018

An nth-letter selector in CSS

Variable fonts are a very exciting and powerful new addition to the toolbox of web design. They was very much at the centre of discussion at this year’s Ampersand conference.

A lot of the demonstrations of the power of variable fonts are showing how it can be used to make letter-by-letter adjustments. The Ampersand website itself does this with the logo. See also: the brilliant demos by Mandy. It’s getting to the point where logotypes can be sculpted and adjusted just-so using CSS and raw text—no images required.

I find this to be thrilling, but there’s a fly in the ointment. In order to style something in CSS, you need a selector to target it. If you’re going to style individual letters, you need to wrap each one in an HTML element so that you can then select it in CSS.

For the Ampersand logo, we had to wrap each letter in a span (and then, becuase that might cause each letter to be read out individually instead of all of them as a single word, we applied some ARIA shenanigans to the containing element). There’s even a JavaScript library—Splitting.js—that will do this for you.

But if the whole point of using HTML is that the content is accessible, copyable, and pastable, isn’t a bit of a shame that we then compromise the markup—and the accessibility—by wrapping individual letters in presentational tags?

What if there were an ::nth-letter selector in CSS?

There’s some prior art here. We’ve already got ::first-letter (and now the initial-letter property or whatever it ends up being called). If we can target the first letter in a piece of text, why not the second, or third, or nth?

It raises some questions. What constitutes a letter? Would it be better if we talked about ::first-character, ::initial-character, ::nth-character, and so on?

Even then, there are some tricksy things to figure out. What’s the third character in this piece of markup?

<p>AB<span>CD</span>EF</p>

Is it “C”, becuase that’s the third character regardless of nesting? Or is it “E”, becuase techically that’s the third character token that’s a direct child of the parent element?

I imagine that implementing ::nth-letter (or ::nth-character) would be quite complex so there would probably be very little appetite for it from browser makers. But it doesn’t seem as problematic as some selectors we’ve already got.

Take ::first-line, for example. That violates one of the biggest issues in adding new CSS selectors: it’s a selector that depends on layout.

Think about it. The browser has to first calculate how many characters are in the first line of an element (like, say, a paragraph). Having figured that out, the browser can then apply the styles declared in the ::first-line selector. But those styles may involve font sizing updates that changes the number of characters in the first line. Paradox!

(Technically, only a subset of CSS of properties can be applied to ::first-line, but that subset includes font-size so the paradox remains.)

I checked to see if ::first-line was included in one of my favourite documents: Incomplete List of Mistakes in the Design of CSS. It isn’t.

So compared to the logic-bending paradoxes of ::first-line, an ::nth-letter selector would be relatively straightforward. But that in itself isn’t a good enough reason for it to exist. As the CSS Working Group FAQs say:

The fact that we’ve made one mistake isn’t an argument for repeating the mistake.

A new selector needs to solve specific use cases. I would argue that all the letter-by-letter uses of variable fonts that we’re seeing demonstrate the use cases, and the number of these examples is only going to increase. The very fact that JavaScript libraries exist to solve this problem shows that there’s a need here (and we’ve seen the pattern of common JavaScript use-cases ending up in CSS before—rollovers, animation, etc.).

Now, I know that browser makers would like us to figure out how proposed CSS features should work by polyfilling a solution with Houdini. But would that work for a selector? I don’t know much about Houdini so I asked Una. She pointed me to a proposal by Greg and Tab for a full-on parser in Houdini. But that’s a loooong way off. Until then, we must petition our case to the browser gods.

This is not a new suggestion.

Anne Van Kesteren proposed ::nth-letter way back in 2003:

While I’m talking about CSS, I would also like to have ::nth-line(n), ::nth-letter(n) and ::nth-word(n), any thoughts?

Trent called for ::nth-letter in January 2011:

I think this would be the ideal solution from a web designer’s perspective. No javascript would be required, and 100% of the styling would be handled right where it should be—in the CSS.

Chris repeated the call in October of 2011:

Of all of these “new” selectors, ::nth-letter is likely the most useful.

In 2012, Bram linked to a blog post (now unavailable) from Adobe indicating that they were working on ::nth-letter for Webkit. That was the last anyone’s seen of this elusive pseudo-element.

In 2013, Chris (again) included ::nth-letter in his wishlist for CSS. So say we all.

Friday, September 28th, 2018

Jongert

Nick demonstrates the responsive power of variable fonts by recreating a lovely design from Jacob Jongert.

Grab that browser window and get squishin’!

Tuesday, September 25th, 2018

Incomplete Open Cubes Revisited

Art, geometry, and code. Sol LeWitt started it. Rob saw it through.

Thursday, September 13th, 2018

The Importance Of Manual Accessibility Testing — Smashing Magazine

This is very timely. I’ve been doing some consulting at a company where they are perhaps a little over-reliant on automated accessibility tests.

Automated accessibility tests are a great resource to have, but they can’t automatically make your site accessible. Use them as one step of a larger testing process.

Tuesday, August 21st, 2018

A Tale of Two Buttons

In defence of the cascade (especially now that we’ve got CSS custom properties).

I think embracing CSS’s cascade can be a great way to encourage consistency and simplicity in UIs. Rather than every new component being a free for all, it trains both designers and developers to think in terms of aligning with and re-using what they already have.

Remember, every time you set a property in CSS you are in fact overriding something (even if it’s just the default user agent styles). In other words, CSS code is mostly expressing exceptions to a default design.

Thursday, August 2nd, 2018

Nutrition Cards for Accessible Components A11Y Expectations

A handy bunch of checklists from Dave for creating accessible components. Each component gets a card that lists the expectations for interaction.

Accessibility: Start with the foundations | susan jean robertson

I encourage you to think about and make sure you are using the right elements at the right time. Sometimes I overthink this, but that’s because it’s that important to me - I want to make sure that the markup I use helps people understand the content, and doesn’t hinder them.

Tuesday, July 31st, 2018

The Accessibility of Styled Form Controls & Friends | a11y_styled_form_controls

A great collection of styled and accessible form elements:

Form controls are necessary in many interfaces, but are often considered annoying, if not downright difficult, to style. Many of the markup patterns presented here can serve as a baseline for building more attractive form controls without having to exclude users who may rely on assistive technology to get things done.

Friday, July 20th, 2018

Short note on progressive ARIA by The Paciello Group

Léonie makes a really good point here: if you’re adding aria attributes to indicate interactions you’re making available through JavaScript, then make sure you also use JavaScript to add those aria attributes.

Transform your type online with variable fonts | Creative Bloq

This is a great interview with Rich on all things related to web typography—including, of course, variable fonts.

I’m so lucky that I literally get to work side by side with Rich; I get to geek out with him about font stuff all the time.