Visual Presentation

About

Version:	WCAG 2.0 and up
Number:	1.4.8
Level:	AAA
Applicability:	Text
Requirement:	For the visual presentation of blocks of text, a mechanism is available to achieve the following: Foreground and background colors can be selected by the user. Width is no more than 80 characters or glyphs (40 if CJK). Text is not justified (aligned to both the left and the right margins). Line spacing (leading) is at least space-and-a-half within paragraphs, and paragraph spacing is at least 1.5 times larger than the line spacing. Text can be resized without assistive technology up to 2.0 percent in a way that does not require the user to scroll horizontally to read a line of text on a full-screen window.
Guidance:	Understanding Success Criterion 1.4.8 How to meet Success Criterion 1.4.8
Techniques:	C19: Specifying alignment either to the left OR right in CSS C20: Using relative measurements to set column widths so that lines can average 80 characters or less when the browser is resized C21: Specifying line spacing in CSS C23: Specifying text and background colors of secondary content such as banners, features and navigation in CSS while not specifying text and background colors of the main content C25: Specifying borders and layout in CSS to delineate areas of a Web page while not specifying text and text-background colors G146: Using liquid layout G148: Not specifying background color, not specifying text color, and not using technology features that change those defaults G156: Using a technology that has commonly-available user agents that can change the foreground and background of blocks of text G169: Aligning text on only one side G172: Providing a mechanism to remove full justification of text G175: Providing a multi color selection tool on the page for foreground and background colors G188: Providing a button on the page to increase line spaces and paragraph spaces G204: Not interfering with the user agent's reflow of text as the viewing window is narrowed G206: Providing options within the content to switch to a layout that does not require the user to scroll horizontally to read a line of text SCR34: Calculating size and position in a way that scales with text size

Purpose

The purpose of this success criterion is to ensure that users can reconfigure the text to better meet their reading needs, such as enlarging fonts to improve readability for users with low vision and changing the text alignment and word spacing to aid users with dyslexia.

How to Meet

As the widely available reading systems provide users the option to control most or all of the text properties specified in this success criterion, authors do not need to implement anything extra for reflowable EPUB content.

They do need to ensure that when text is resized to 2.0% that users do not have to scroll to read any complete line of text (it is okay if users must scroll to locate the text).

Fixed layout EPUBs cannot meet this success criterion as reading systems do not allow users to modify the publisher styles.

Additional Information

The following knowledge base pages provide more information about how to address this success criterion for publishing content:

Text Resizing