Accessibility
This site should be usable whatever you are reading it with. This page says what we have done, what we know is imperfect, and how to tell us when we have got it wrong.
What we aim for
WCAG 2.1 Level AA as the working standard.
What that means here
- Text contrast meets or exceeds the AA ratio against every background it sits on, including the dark sections.
- Color is never the only signal. The percentile bar carries labeled values, and every state is stated in words as well as shown in color, so nothing depends on distinguishing two hues.
- Keyboard. Every link, control, accordion and form field is reachable and operable by keyboard, with a visible focus outline. A skip link goes straight to the content.
- Structure. Real headings in order, real lists, real tables with header cells, and landmarks so a screen reader can navigate by region.
- Works without JavaScript. The FAQ accordions, navigation and forms all function with scripting disabled; JavaScript only improves them.
- Tables scroll rather than breaking the layout on a narrow screen, and text reflows without a horizontal scrollbar down to a small phone.
- Type is set in relative units, so browser zoom and your own font size preferences work.
Where we know we fall short
The drawn charts and infographics carry alternative text describing what they show, but a complex distribution chart is genuinely hard to convey in a sentence. Where a graphic carries figures, those figures are also in the surrounding text or in a table — if you find one where they are not, that is a bug and we want to hear about it.
Content embedded from elsewhere is outside our control and may not meet the same standard.
Tell us
If something here is difficult or impossible to use, please tell us what you were trying to do and what you were using. That is far more useful than a general report, and we will fix what we can and say so when we cannot.