Checkpoint 7.5 - Core
All font sizes use relative units and not absolute units
WCAG 1.0 Priority 2
WCAG Guideline 3. Use markup and style sheets and do so properly.
Relatively sized text allows users to have some control over the size of font they wish to view by adjusting settings in the browser. Absolute sized text cannot be manipulated in the same manner. The screen resolution of the user's browser may make the text difficult to read if absolute sizing is used and the user is not able to adjust text size manually.
Requirement
Do not use absolute values for sizing and positioning. Text must be resizable to enable users to have some visual control over font size via their browser settings. This should be done using percentages (%) or ems (em). Text size is to be specified in the stylesheet.
Recommendation
Resize the browser to the smallest size and to the largest size to test that the page is usable.
Checking Tool
- Internet Explorer - AIS toolbar:
IE Options > Text Size > Largest/Smallest
Information Source
The original source of this information is located on the W3C web site (www.w3.org/TR/WCAG10-TECHS/#tech-relative-units)