Accessibility Checkpoint WCAG 2 1.4.4
Use relative rather than absolute units in CSS property values.
Absolute units are CM, MM, IN, PC and PT. When used with fonts PX is also considered an absolute unit, because it isn’t relative the user’s preferred font size. Low-vision users, and a lot of people over 50, increase the browser default font size to make text easier to read. Absolute units ignore this user choice. Relative units like EM and percentages «stretch» according to the screen size and/or user’s preferred font size, and work on a large range of devices.
Note: Section 508 Refresh (2017) checkpoints are equivalent to WCAG 2.0 level AA checkpoints.
- 5.23 Oct 2016 Fixed false positive on fallbacks.
- 5.22 Jul 2016 Fixed false positive on print media.
- 5.3 Sep 2013 Fixed false positive.
- 5.2 May 2013 Corrected WCAG 2 priority level (was A instead of AA).
- 4.5 Nov 2011 Don’t complain about using absolute units when zero used (because 0px = 0pt = 0em = 0%).
- 4.3 Apr 2011 Pick up CSS absolute units used in font: shorthand as well as font-size:.
- 4.3 Apr 2011 Now triggers WCAG 2 1.4.4.
- 3.5 Dec 2009 Modified rule to match intention of original author of guideline: http://lists.w3.org/Archives/Public/w3c-wai-gl/2004JanMar/0187.
- 3.0 Dec 2008 Now triggers WCAG2 issue.
- 1.0 Feb 2007 Added.
This page describes a web site issue detected by SortSite Desktop and OnDemand Suite.
Rule ID: AccWcag1-3.4.1