Default Stylesheet for non-reflowable EPUB contents e.g. reading mode

[JayPanoz]

I'm submitting a topic for discussion, as requested by @HadrienGardeur during the monthly call yesterday.

Short description of the issue/suggestion:

At the moment ReadiumCSS is providing styles that are designed specifically for reflowable EPUB contents.

In the foreseeable future, Reading Apps may implement features such as Reading Mode for other contents and it could be useful ReadiumCSS provides styles for such.

Let’s use this issue as a place to discuss needs and requirements.

[gautierchomel]

Reading Mode is a simplified view intending to provide fluid content from a complex design.

Apart from vanilla styles for structure tags, there's also to consider that complex design is usually a vehicle for semantics through visual enhancement. This feature should be considered from an assistive technology approach.

Therefore, Reading Mode should implement a verbosity setting, allowing the injection of semantic content. Few examples:

• page numbers (see Thorium discussion #1951 )
• DPub Aria Roles (see DAISY Transitiontoepub repo).

This list is non exhaustive and should be a starting point for discussion.

[gautierchomel]

Also, because most fixed layout ebooks are not designed to be reflowed, there are probably some warnings to implement. Those could be based on metadata present or inferred.