No independent accessibility audit has been carried out, and no disabled person has tested this app with the assistive technology they use. Everything above was measured by us, on our own machines, against the criteria we chose to measure.
The app has not been checked at double the browser’s zoom, or in a window as narrow as a small phone held sideways. Those are real WCAG requirements about text reflowing rather than being cut off, and we have not put a number on either.
Contrast is measured for text. It is not measured for the outlines, borders and focus rings around controls, except for the one search field where we replaced a missing focus ring and checked its colour.
In the picture-matching activities the options are pictures, so a screen reader announces the picture symbol itself. Somebody working entirely by ear cannot currently tell those options apart. This is the clearest known gap in the app, and it is a consequence of a design that carries meaning by picture and sound so that reading is never required first.
The High Contrast setting darkens text that has no colour of its own. Text that carries a specific colour keeps it, so the setting does less than its name suggests.
Contrast is swept on the pages the test can reach when it runs. A page it did not open is a page nobody measured, and the test prints the list of what it opened so that gap is visible rather than assumed.