Technique 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:

1.4.1: Use of Color (Advisory)
2.4.7: Focus Visible (Sufficient)

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:

<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:

#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.

<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: #1E2EB8; 
        color: #FFF;
      }
    </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>

Working example of this code: Example of highlighting elements that receive focus.

Other sources

No endorsement implied.

Tests

Procedure

For each element able to attain focus:

Using a mouse, hover over the element.
Check that the background or border changes color.
Move the mouse away from the object before attempting keyboard focus.
Using a keyboard, tab to the element.
Check that the background or border changes color.
Check that the background or border changes in color are removed when the element loses focus.

Expected Results

Checks #2, #5 and #6 are true.