About this site
Accessibility
This site aims to be easy to use for everyone, whatever device, browser or assistive technology you use.
The standard
The site is built to meet the Web Content Accessibility Guidelines (WCAG) 2.2 at level AA.
What that means here
- Every page can be used with a keyboard alone, with a visible focus outline and a link to skip to the main content.
- Every text colour has been checked against its background for contrast.
- Every image has a written description.
- Every form field has a label, and any problem is explained next to the form.
- If you have asked your device to reduce motion, the site does not animate.
- Text can be enlarged in your browser without anything being cut off.
Reading the free chapters
The on-screen reader has a text size control and three page colours: light, sepia and dark. It remembers your choice on your device.
Something not working?
Please say so through the contact form, with the page and what went wrong. Problems are fixed as quickly as possible.
Last reviewed: October 2026.