Appearance and themes

Umbra styles widgets through design tokens, so one setting restyles every widget that follows them. Changes apply live.

Appearance settings

In Settings → Appearance → Customize colors, text and size:

Setting	Effect
Corner radius	default, sharp or round. Overrides the theme’s --radius-s/m/l.
Accent color	A color of your choice, or Match Windows accent, which follows the system accent live (lightened if it is too dark for black). Empty uses the theme’s accent.
Interface font and size	Sets --font and --font-scale. Widgets that size text in em/rem follow the scale.
Light text	Brighter --text* colors.
Window border	On or off, and its color.
Reduce transparency	Solid --line* and --accent-soft, opaque windows.
Animation speed	normal, calm (animation durations doubled) or off. Windows’ reduced-motion preference is respected.
Size of new widgets	The starting scale for new widgets, 0.5 to 3.

The same settings from a terminal:

umbractl general --corner-radius round --animation-speed calm
umbractl set-general --accent "#ff7a59" --light-text on --ui-font Consolas --font-scale 1.1 --border off --reduce-transparency on

Themes

A theme restyles every widget at once: surfaces, lines, text, accent, up/down colors and corner radii. Switch in Settings → Appearance, or:

umbractl themes                  # installed themes and the community catalog
umbractl install-theme ember     # install from the catalog
umbractl theme ember             # switch, live (`umbractl theme default` for Umbra Black)
umbractl remove-theme ember

“Umbra Black” is the built-in default. The catalog ships Ember, Glacier and Mono. Themes are data only: a list of named color and radius tokens with strict value checks, never code, so a theme can’t load anything. Your own appearance settings (accent, corner radius, font) are applied on top of the theme.

Widgets that set "themeable": false in their manifest keep their own look. To make a theme, see Build a theme.

Windows contrast themes

When Windows has a contrast theme on, Umbra maps the tokens to system colors and ignores themes and accents, so widgets stay readable. Widget authors can read about it in the styling guide.