Accessibility

Windows High Contrast Mode

Windows users are offered a number of high contrast themes at the operating system level — some light-on-dark like our inverted theme. In addition to supplying our theme switcher feature, it’s important to make sure WHCM is supported as well as possible. Here are some tips:

  • Do not use background images as content. Not only will this invert the images in our inverted dark theme, but they’ll be eliminated entirely in most Windows high contrast themes. Provide salient, non-decorative images in <img/> tags with descriptive alt text values
  • For inline SVG icons, use the currentColor value for fill and stroke. This way, the icon color will change along with the surrounding text color when the high contrast theme is activated.
  • If you need to detect WHCM to make special amendments, you can use the following media query:

CSS

@media (-ms-high-contrast: active) { 
  /* WHCM-specific code here */
}

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Light/Dark Theme Switcher using CSS Invert Filter

Here’s a really straightforward dark theme switcher for light designs. It uses the CSS invert() filter and minimal JavaScript to switch it on and off.

Screenshots of The Boston Globe and The Independent with the CSS invert filter applied.
The Boston Globe and The Independent with the CSS invert filter applied.

CSS

:root { 
   background-color: #fefefe;
   filter: invert(100%);
}
 
* { 
   background-color: inherit;
}
 
img:not([src*=".svg"]), video {  
   filter: invert(100%);
}

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Solutions for creating more accessible SVGs

We’ve been working with SVGs a lot recently, which has led our developers down a rabbithole of discovery! Here are some things to consider when it comes to SVGs and accessibility.

[…]

1. <img> tags and SVGs

When SVGs are implemented as <img> tags with an .svg as the source, we’ve encountered a few issues for VoiceOver and TalkBack users. These issues occur when those <img> tags don’t also have an ARIA role=”img” attribute.

[…]

2. <title> tags and SVGs

We often see examples of making SVGs accessible by simply adding a <title> element within the inline <svg>. While this does help in some situations, like a lone SVG icon within a link, adding a <title> element doesn’t make SVGs accessible in all browsing environments.

[…]

For example, when using Firefox and NVDA, a link containing an SVG would be recognized as a link, but the text within the <title> element would not be announced. NVDA announces the path within the href attribute only.

Adding an aria-labelledby attribute to the SVG can help expose the text within the <title> element to the browser’s accessibility API. However, even with this in place, NVDA does not announce the <title> text as we might expect.

Our most recommended approach when it comes to browser support and consistency across screen readers is to add a visually-hidden element as a sibling element to the <svg>. With this implementation, we’ve found that all browser and screen reader combinations tested were able to announce the link with the expected text announcement.

We also recommend adding aria-hidden=”true” to the <svg> element itself. This is to help prevent having any other text that may be embedded within the SVG be announced by screen readers. Then, the only text that should be announced would be the content within that visually-hidden element.

[…]

7. Colour contrast

While not a bug per se, we also see a lot of cases where designers and developers don’t plan for colour contrast issues for SVGs. Since SVGs function just like transparent GIFs in how they are displayed, different page background colors and effects can cause unanticipated issues for low vision users.

For example, a black SVG icon that’s perfectly visible with a white page background is going to be invisible in a Windows High Contrast theme that uses a black background. This is a common use case for users who use High Contrast settings due to light sensitivity or related issues. When you provide a solid background or contrasting border for SVGs, you can help avoid those kinds of problems.

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Responsive Design for Motion, a.k.a. "prefers-reduced-motion" Media Query

WebKit now supports the prefers-reduced-motion media feature, part of CSS Media Queries Level 5, User Preferences. The feature can be used in a CSS @media block or through the window.matchMedia() interface in JavaScript. Web designers and developers can use this feature to serve alternate animations that avoid motion sickness triggers experienced by some site visitors.

To explain who this media feature is for, and how it’s intended to work, we’ll cover some background. Skip directly to the code samples or prefers-reduced-motion demo if you wish.

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Inclusive Toggle Buttons

How you design and implement your toggle buttons is quite up to you, but I hope you’ll remember this post when it comes to adding this particular component to your pattern library. There’s no reason why toggle buttons — or any interface component for that matter — should marginalize the number of people they often do.

You can take the basics explored here and add all sorts of design nuances, including animation. It’s just important to lay a solid foundation first.

Checklist

  • Use form elements such as checkboxes for on/off toggles if you are certain the user won’t believe they are for submitting data.
  • Use <button> elements, not links, with aria-pressed or role="switch" plus aria-checked.
  • Don’t change label and state together.
  • When using visual “on” and “off” text labels (or similar) you can override these with a unique label via aria-labelledby.
  • Be careful to make sure the contrast level between the button’s text and background color meets WCAG 2.0 requirements.

See the source link for very detailed descriptions of all of these points.

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Introducing A11y Dialog

Almost all projects involve some form of dialog window at one point or another. However, accessibility is all too often set aside in favor of quick implementation. Truth is, accessible dialog windows are hard. Very hard.

Fortunately, there is a super clever guy named Greg Kraus who implemented an accessible modal dialog a few years ago and open-sourced it on GitHub. Now that’s nice!

However, his version—no matter how good it is—requires jQuery. We try to avoid using jQuery as much as we can here. We realised we did not really need it most of the time. On top of that, his script is not very flexible: only one dialog window per page, hard-coded IDs inside the functions. Not very practical and certainly not a drop-in script for any project.

So I rolled up my sleeves and improved it.

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