One source of truth for GTK 4 and Qt 6.
Color
Every colour carries a light and a dark value. Components reference the token, never the hex — switching the theme resolves the second value. Click a swatch to copy its CSS variable.
Typography
Inter for the interface, JetBrains Mono for values, shortcuts and code. Nine steps cover every surface in both toolkits.
Radius
Five radii. Tile, control and card exist as variables in the design file; menu and pill are documented constants used inline.
Spacing
A 4px rhythm. Anything outside this scale is a bug.
Metrics
Fixed sizes that make a GTK window and a Qt window line up pixel for pixel.
Elevation
Three levels. Transient surfaces sit one level above the window and keep the 12px card radius.
States
Hover and pressed are background shifts, never colour changes. Focus is always a visible accent ring.
Usage
Three consumers, one build step. The generated files are the only thing an app links against.