Input fields and data entry elements maintain a contrast ratio of at least 3:1 against their background in all states.
Insufficient checkbox contrast:
This checkbox has an insufficient contrast ratio (1.16:1) against the background:
Note: Possible to automatically test. This can be achieved by programmatically retrieving the current color (i.e. CSS color property, or otherwise) of an element and verifying that it has sufficient contrast against its background. However, a human tester or AI is most likely needed to confirm full visibility.