Keyboard and focus
All site controls are keyboard reachable and use visible focus states. Escape leaves the typing capture, and the trainer does not intercept browser shortcuts that use Control, Command, or Alt.
Visual access
The interface supports light and dark themes, strong text contrast, responsive text, and a reduced-motion preference. Correct and incorrect characters differ by more than color alone.
Screen readers
Controls have programmatic labels, results use semantic headings and tables, status changes use restrained live regions, and decorative icons are hidden from assistive technology.
Known constraint
A physical keyboard provides the most meaningful latency and finger-layout measurements. Mobile users can still type, but on-screen keyboard behavior varies by device.