Techniques for WCAG 2.0

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C13: Using named font sizes



This technique relates to:

User Agent and Assistive Technology Support Notes

See User Agent Support Notes for C13.


The objective of this technique is to specify a named font size that expresses the relative font size desired. These values provide hints so that the user agent can choose a font-size relative to the inherited font-size.


Example 1: Named font sizes in CSS

This example selects a larger font size for strong elements so that their text will always be larger than the surrounding text, in whatever context they are used. Assuming that headings and paragraphs use different font sizes, the emphasized words in this example will each be larger than their surrounding text.

Example Code:

strong {font-size: larger}


<h1>Letting the <strong>user</strong> control text size</h1>
<p>Since only the user can know what size text works for him, 
it is <strong>very</strong> important to let him configure the text size.  


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  1. Check that the value of the CSS property that defines the font size is one of xx-small, xx-small, x-small, small, medium, large, x-large, xx-large, xsmaller, or larger.

Expected Results

If this is a sufficient technique for a success criterion, failing this test procedure does not necessarily mean that the success criterion has not been satisfied in some other way, only that this technique has not been successfully implemented and can not be used to claim conformance.

Techniques are Informative

Techniques are informative—that means they are not required. The basis for determining conformance to WCAG 2.0 is the success criteria from the WCAG 2.0 standard—not the techniques. For important information about techniques, please see the Understanding Techniques for WCAG Success Criteria section of Understanding WCAG 2.0.