Links does not follow WCAG

[SifAa]

WCAG 2.0 criterion 1.4.1 says colour is not to be used as the only means of distinguishing a visual element such as links. It would be good if preferences could include settings like underline links or something similar.

[JayPanoz]

This would have to be added to Readium CSS, ideally, as it is responsible for applying styles in EPUB and WebPub. Maybe we could plan some additional a11y features in a new submodule that we can then expose through the Preferences API.

If we are starting with links and underline, there is probably more we could handle in WCAG.