What does “Focus Visible” require regarding contrast?

The concept of "Focus Visible" is a fundamental principle in web accessibility, particularly concerning how users navigate using keyboard controls. The requirement for sufficient contrast against the adjacent background when an element is focused ensures that users who rely on keyboard navigation can easily distinguish which element is currently active. This is essential for users with visual impairments, as well as those who may not use a mouse.

When an element receives focus—whether it be a link or a form input—it is important that this focused state is visually recognizable. Sufficient contrast helps to prevent confusion and allows users to navigate websites more effectively, directly impacting their engagement and usability experience.

By requiring that the focused element stands out against its background, "Focus Visible" enhances accessibility for all users, particularly those with low vision. This principle fosters an inclusive design that aids in navigation and interaction within digital content.