From an OpenStax Blog Post:
While creating our library of over 40 free, peer-reviewed, openly licensed textbooks for high school and college courses, we’ve placed both affordability and accessibility at the forefront. Although we’ve had several accessibility initiatives since publishing our first textbook in 2012, we also recognize that accessibility is an ever-changing landscape.
When designing our textbooks, we’ve prioritized making the text in our books (which includes headers, features, and exercises) reader-friendly on-screen. For example, the content in our math textbooks is rendered in MathML, an accessible format that can be read with screen readers and styled with CSS. We’ve also prioritized accessibility by making some of our textbooks available through Bookshare in Braille Ready Format and/or Digital Accessible Information System (DAISY) formats. With Braille Ready Format, our online text can be used to produce embossed braille, read with a braille display, or read using a refreshable braille device. Meanwhile, DAISY is a specification for a special form of text-to-speech that features more detail than just a reading of the body text. The Bookshare text also features a color-grading tool that helps to reduce strain and make focus easier when reading through blocks of digital text.
At OpenStax, our goal is to meet WCAG 2.0 accessibility guidelines at Level AA. Although our developers are working diligently to resolve accessibility issues, we know that there are still improvements we need to make to make our books more accessible for all. This year, our developers are working on enhancing reading accessibility by bringing the default font size up to 16ptx, in line with WCAG 2.0 guidelines. Our developers are also working on adding a feature that would allow users to make the font size bigger or smaller, without having to zoom in or out of their entire web browser.