A set of reference stylesheets for EPUB Reading Systems.
Readium CSS provides styles for reflowable text:
- paged and scrolled views;
- a “patch” for HTML5 Suggested Rendering specific to publications (e.g. extra styles for hyphenation, breaks, etc.);
- default styles for unstyled ebooks;
- theming;
- user settings;
- a set of baselines and recommendations for accessibility, overrides, and internationalization.
See license.txt.
The primary goal of Readium CSS is to provide Reading System implementers with reliable and modern styles for reflowable EPUB 2 and EPUB 3 files. In addition, it should provide good interoperability in the existing ecosystem, while not overriding authors’ styles unless strictly necessary.
Readium CSS stylesheets were not designed and should not be used for fixed-layout EPUB, nor other file formats like FB2, PRC, Mobi, TEI, etc.
Some issues, which may be raised during development, will be documented so that they can serve as a reference for revisions of the EPUB specification, and even future specifications.
Readium CSS is implemented in the Readium Mobile and Readium Web projects.
You will find it in:
External use include:
Active development is pulled in branch develop.
Building and testing are relying on npm packages and scripts. To initialize your clone/fork, first install dev dependencies:
npm install
In case you’re encountering an error with Puppeteer, make sure you’re using at least Node v.20.11.1 – it might work with an earlier version but only the latest LTS as of March 21, 2024 has been tested.
Then create reference bitmaps for visual regression testing:
npm run test:ref
To transpile all stylesheets using PostCSS:
npm run build
To test the updated styles and catch visual regression bugs:
npm run test
To update reference bitmaps after a bugfix:
npm run test:approve
Documentation can be accessed in docs.