What is built in
The site uses semantic headings and page regions, a skip-to-content link, visible keyboard focus, labelled form controls and text alternatives for illustrations. It supports narrow screens, browser zoom and a reduced-motion preference. Meaning does not rely on colour alone.
Navigation and article content remain available without JavaScript. Search, calculations and quiz progression need JavaScript, with explanations or worked examples provided when it is disabled. Tables can scroll horizontally without requiring the whole page to scroll sideways.
Keyboard and controls
Use Tab and Shift+Tab to move through links and controls. Enter activates links; Enter or Space operates buttons and question panels. On small screens, the menu button opens the navigation, and Escape closes it. Calculator errors and quiz feedback use live text announcements.
Assessment and known limits
This is not an independent accessibility certification or a claim of full WCAG conformance. Automated layout, keyboard and functionality checks can find some issues but do not replace testing with assistive-technology users. Complex explanatory images are supplemented by text; external destinations are outside this website’s control.
Report an accessibility issue
Contact the publisher through the contact page when its details are completed. Tell us the page, the difficulty and the device or assistive technology involved. Avoid including passwords, private account information or unnecessary personal data.