Techniques for WCAG 2.0

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# C15: Using CSS to change the presentation of a user interface component when it receives focus

## Applicability

CSS, HTML and XHTML

This technique relates to:

- Success Criterion 1.4.1 (Use of Color)
  - How to Meet 1.4.1 (Use of Color)
  - Understanding Success Criterion 1.4.1 (Use of Color)
- Success Criterion 2.4.7 (Focus Visible)
  - How to Meet 2.4.7 (Focus Visible)
  - Understanding Success Criterion 2.4.7 (Focus Visible)

## User Agent and Assistive Technology Support Notes

Internet Explorer 6.0 and earlier versions for Windows do not support dynamic pseudo-classes for any elements except hyperlinks. Internet Explorer 7 does not support :focus styles for elements other than hyperlinks. Include the :active CSS pseudo class to achieve the same effect as :focus in Internet Explorer for (X)HTML links (a element).

Firefox 1.5, Firefox 2.0 and SeaMonkey 1.1 for Windows support dynamic pseudo-classes for text input fields, text areas, radio buttons, check boxes, select elements, submit/reset buttons, and button elements. However, setting different colors or borders when a radio button or a check box receives focus is not supported.

Opera 9.02 for Windows supports dynamic pseudo-classes for text input fields, text areas, radio buttons, check boxes, select elements, submit/reset buttons, but not for button elements.

Firefox 2.0, Opera 9.02 and SeaMonkey 1.1 for Windows also support adjacent sibling selectors for form labels. Firefox 1.5, Internet Explorer 6.0 and earlier versions for Windows do not support adjacent sibling selectors for form labels.

## Description

The objective of this technique is to demonstrate how visual appearance may be enhanced via style sheets to provide visual feedback when an interactive element has focus or when a user hovers over it using a pointing device. Highlighting the element that has focus or is hovered over can provide information such as the fact that the element is interactive or the scope of the interactive element.

Providing visual feedback may be possible through more than one mode. Usually, it is attained through using a mouse to hover over the element or a keyboard to tab to the element.

## Examples

### Example 1: Link elements

In this example, mouse and keyboard focus indicators have been applied to the link elements. CSS has been used to apply a background color when the link elements receive focus.

Here is the content to be displayed:

Example Code:

    <ul id="mainnav">
      <li class="page_item">Home</li>
      <li class="page_item"><a href="/services">Services</a></li>
      <li class="page_item"><a href="/projects">Projects</a></li>
      <li class="page_item"><a href="/demos">Demos</a></li>
      <li class="page_item"><a href="/about-us">About us</a></li>
      <li class="page_item"><a href="/contact-us">Contact us</a></li>
      <li class="page_item"><a href="/links">Links</a></li>
    </ul>

Here is the CSS that changes the background color for the above elements when they receive mouse or keyboard focus:

Example Code:

    #mainnav a:hover, #mainnav a:active, #mainnav a:focus {
      background-color: #DCFFFF;
      color:#000066;
    }

### Example 2: Highlighting elements that receive focus

In this example, the :focus pseudo-class is used to change the style applied to input fields when they receive focus by changing the background color.

Example Code:

    <html>
      <head>
        <style type="text/css">
          input.text:focus {
            background-color: #7FFF00; color: #000;
          }
          input[type=checkbox]:focus + label, input[type=radio]:focus + label {
            background-color: #FF6: color: #000;
          }
        </style>
      </head>
      <body>
        <form method="post" action="form.php">
          <p><label for="fname">Name: </label>
            <input class="text" type="text" name="fname" id="fname" />
          </p>
          <p>
            <input type="radio" name="sex" value="male" id="sm" /> <label for="sm">Male</label><br />
            <input type="radio" name="sex" value="female" id="sf" /> <label for="sf">Female</label>
          <p>
        </form>
      </body>
    </html>

## Resources

Resources are for information purposes only, no endorsement implied.

- CSS 2.0: 5.11.3 The dynamic pseudo-classes: :hover, :active, and :focus

- CSS 2.0: 5.7 Adjacent sibling selectors

## Tests

### Procedure

For each element able to attain focus:

1. Using a mouse, hover over the element.

2. Check that the background or border changes color.

3. Move the mouse away from the object before attempting keyboard focus.

4. Using a keyboard, tab to the element.

5. Check that the background or border changes color.

6. Check that the background or border changes in color are removed when the element loses focus.

### Expected Results

- Checks #3, #5 and #6 are true.

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