Techniques for WCAG 2.0

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C24: Using percentage values in CSS for container sizes

Important Information about Techniques

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.


Pages that use CSS.

This technique relates to:


The objective of this technique is to enable users to increase the size of text without having to scroll horizontally to read that text. To use this technique, an author specifies the width of text containers using percent values.


Example 1

A newspaper has content in the middle of the window. The width of the container for the content is specified in page percentages, so that when a person with low vision increases the font size the text reflows inside the browser window at the new size and there is no need to scroll horizontally.



  1. Check that all container widths are specified as percentage values.

  2. Increase the text size to 200%.

  3. Check to make sure that horizontal scrolling is not required to read any line of text.

  4. Check that all text is still visible on the page.

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.