Content managed via styles is provided with an appropriate alternative
Some CSS instructions display text and images that are actually invisible to users and tools that do not support stylesheets. For example, when disabling CSS colors or styles, a CSS image (property of background-image) will not be visible while an HTML image (element ) would have been displayed.
Objectives
Allow users in contexts or styles are not rendered (text browser, screen reader, browser with disabled styles) to access the current information in the form of CSS managed content (background images in particular).
Improve accessibility of content to readers with disabilities.
Implementation
Provide hidden content to display via CSS :
for each information carried by CSS background-image or content properties;
for each information displayed via a pseudo-element CSS :before or :after;
and more generally, for every information that is otherwise absent from the page and whose rendering depends on style support.
Control
Control is done at the time of the digital book design by paying particular attention to the use of the pseudo-elements CSS before or :after and CSS background-image. The normal display of the relevant page will be compared visually with its rendering after turning off background images. The display will be compared with and without background images.