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56 lines
3.6 KiB
Markdown
56 lines
3.6 KiB
Markdown
---
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layout: docs
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title: Accessibility
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group: getting-started
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---
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Bootstrap follows common web standards and—with minimal extra effort—can be used to create sites that are accessible to those using <abbr title="Assistive Technology" class="initialism">AT</abbr>.
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## Component requirements
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Some common HTML elements are always in need for basic accessibility enhancements through `role`s and Aria attributes. Below is a list of some of the most frequently used ones.
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{% callout info %}
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**Heads up!** As we go through the alphas, we'll be moving more accessibility notes here with links to specific sections from other areas of the docs.
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{% endcallout %}
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### Button groups
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In order for assistive technologies–such as screen readers–to convey that a series of buttons is grouped, an appropriate `role` attribute needs to be provided. For button groups, this would be `role="group"`, while toolbars should have a `role="toolbar"`.
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In addition, groups and toolbars should be given an explicit label, as most assistive technologies will otherwise not announce them, despite the presence of the correct `role` attribute. In the examples provided here, we use `aria-label`, but alternatives such as `aria-labelledby` can also be used.
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## Skip navigation
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If your navigation contains many links and comes before the main content in the DOM, add a `Skip to main content` link before the navigation (for a simple explanation, see this [A11Y Project article on skip navigation links](http://a11yproject.com/posts/skip-nav-links/)). Using the `.sr-only` class will visually hide the skip link, and the <code>.sr-only-focusable</code> class will ensure that the link becomes visible once focused (for sighted keyboard users).
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{% callout danger %}
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Due to long-standing shortcomings/bugs in Chrome (see [issue 262171 in the Chromium bug tracker](https://code.google.com/p/chromium/issues/detail?id=262171 "Chromium bug tracker - Issue 262171: Focus should cycle from named anchor")) and Internet Explorer (see this article on [in-page links and focus order](http://accessibleculture.org/articles/2010/05/in-page-links/)), you will need to make sure that the target of your skip link is at least programmatically focusable by adding `tabindex="-1"`.
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In addition, you may want to explicitly suppress a visible focus indication on the target (particularly as Chrome currently also sets focus on elements with `tabindex="-1"` when they are clicked with the mouse) with `#content:focus { outline: none; }`.
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Note that this bug will also affect any other in-page links your site may be using, rendering them useless for keyboard users. You may consider adding a similar stop-gap fix to all other named anchors / fragment identifiers that act as link targets.
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{% endcallout %}
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{% highlight html %}
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<body>
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<a href="#content" class="sr-only sr-only-focusable">Skip to main content</a>
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...
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<div class="container" id="content" tabindex="-1">
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<!-- The main page content -->
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</div>
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</body>
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{% endhighlight %}
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## Nested headings
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When nesting headings (`<h1>` - `<h6>`), your primary document header should be an `<h1>`. Subsequent headings should make logical use of `<h2>` - `<h6>` such that screen readers can construct a table of contents for your pages.
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Learn more at [HTML CodeSniffer](http://squizlabs.github.io/HTML_CodeSniffer/Standards/Section508/) and [Penn State's Accessability](http://accessibility.psu.edu/headings).
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## Additional resources
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- ["HTML Codesniffer" bookmarklet for identifying accessibility issues](https://github.com/squizlabs/HTML_CodeSniffer)
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- [The A11Y Project](http://a11yproject.com/)
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- [MDN accessibility documentation](https://developer.mozilla.org/en-US/docs/Accessibility)
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