Themes and appearance

Appearance is themed with plain CSS custom properties. There is no CSS framework and no theming library — a theme is a set of variable values, which means a theme is small, readable, and cannot break layout by accident.

The presets

Several schemes ship with the application, including light and dark variants and presets chosen for accessibility rather than for looks.

Contrast is tested, not asserted

Theme colour pairings are checked automatically in the test suite. Adding a new foreground/background pairing brings it under that check without anyone remembering to add it — which matters, because contrast regressions are the kind of thing that is invisible to the person who introduced them and obvious to the person who needs the contrast.

Focus indication

Keyboard focus is always visible in every theme. The platform web view omits the :focus-visible state when focus is moved by code rather than by the user, so a plain :focus fallback is present specifically to cover that case.

Reduced motion

Where the operating system reports a preference for reduced motion, animation and transition are suppressed.