See Understanding Techniques for WCAG Success Criteria for important information about the usage of these informative techniques and how they relate to the normative WCAG 2.0 success criteria. The Applicability section explains the scope of the technique, and the presence of techniques for a specific technology does not imply that the technology can be used in all situations to create content that meets WCAG 2.0.
CSS
This technique relates to:
Note: This technique must be combined with other techniques to meet SC 1.4.4. See Understanding SC 1.4.4 for details.
Note: This technique must be combined with other techniques to meet SC 1.4.8. See Understanding SC 1.4.8 for details.
The objective of this technique is to specify text font size in em units so that user agents can scale content effectively. Since the em is a property of the font, it scales as the font changes size. If a font-size is specified for the body element, all other elements inherit that value, unless overridden by a more specific selector.
This example defines the font size for strong element so that its text will always be larger than the surrounding text, in whatever context it is used. Assuming that headings and paragraphs use different font sizes, the strong words in this example will each be larger than their surrounding text.
Example Code:
strong {font-size: 1.6em}
...
<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. </p>
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Check that the value of the CSS property that defines the font size is expressed in em units.
Check #1 is true
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.