[ipfire.org.git] / src / scss / bootstrap-4.0.0-alpha.6 / docs / getting-started / accessibility.md

---
layout: docs
title: Accessibility
description: Learn how Bootstrap supports common web standards for making sites that are accessibile to those using assistive technology.
group: getting-started
---

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>.

## Contents

* Will be replaced with the ToC, excluding the "Contents" header
{:toc}

## Component requirements

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.

### Button groups

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"`.

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.

## Skip navigation

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).

{% callout danger %}
Due to long-standing shortcomings/bugs in 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"`.

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; }`.

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.
{% endcallout %}

{% highlight html %}
<body>
  <a href="#content" class="sr-only sr-only-focusable">Skip to main content</a>
  ...
  <div class="container" id="content" tabindex="-1">
    <!-- The main page content -->
  </div>
</body>
{% endhighlight %}

## Nested headings

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.

Learn more at [HTML CodeSniffer](https://squizlabs.github.io/HTML_CodeSniffer/Standards/Section508/) and [Penn State's Accessability](http://accessibility.psu.edu/headings/).

## Additional resources

- ["HTML Codesniffer" bookmarklet for identifying accessibility issues](https://github.com/squizlabs/HTML_CodeSniffer)
- [The A11Y Project](http://a11yproject.com/)
- [MDN accessibility documentation](https://developer.mozilla.org/en-US/docs/Web/Accessibility)
Commit	Line	Data
91e44d91 S	1	---
	2	layout: docs
	3	title: Accessibility
	4	description: Learn how Bootstrap supports common web standards for making sites that are accessibile to those using assistive technology.
	5	group: getting-started
	6	---
	7
	8	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>.
	9
	10	## Contents
	11
	12	* Will be replaced with the ToC, excluding the "Contents" header
	13	{:toc}
	14
	15	## Component requirements
	16
	17	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.
	18
	19	### Button groups
	20
	21	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"`.
	22
	23	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.
	24
	25	## Skip navigation
	26
	27	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).
	28
	29	{% callout danger %}
	30	Due to long-standing shortcomings/bugs in 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"`.
	31
	32	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; }`.
	33
	34	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.
	35	{% endcallout %}
	36
	37	{% highlight html %}
	38	<body>
	39	<a href="#content" class="sr-only sr-only-focusable">Skip to main content</a>
	40	...
	41	<div class="container" id="content" tabindex="-1">
	42	<!-- The main page content -->
	43	</div>
	44	</body>
	45	{% endhighlight %}
	46
	47	## Nested headings
	48
	49	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.
	50
	51	Learn more at [HTML CodeSniffer](https://squizlabs.github.io/HTML_CodeSniffer/Standards/Section508/) and [Penn State's Accessability](http://accessibility.psu.edu/headings/).
	52
	53	## Additional resources
	54
	55	- ["HTML Codesniffer" bookmarklet for identifying accessibility issues](https://github.com/squizlabs/HTML_CodeSniffer)
	56	- [The A11Y Project](http://a11yproject.com/)
	57	- [MDN accessibility documentation](https://developer.mozilla.org/en-US/docs/Web/Accessibility)