Shape

themes specs/themes/shape.kmd

Shape system — corner-radius scale, when to use which radius, and per-preset variation rules. Material parity (`/styles/shape/overview-principles`). Every UI element binds its corner radius to a role from this scale; per-preset overrides come from `ui-style.kmd`.

When this spec applies

Primary triggers

Apply corner radius to any container, button, or surface

All triggers

Pick corner radius for a new component
Tune shape for a new preset
Audit shape consistency across a screen

Spec — Shape

Facet Visual do Koder Design. Material parity: https://m3.material.io/styles/shape/overview-principles.

The shape scale (5 levels)

Role	Default radius (px)	Use
`radius-none`	0	Sharp corners — Bauhaus, brutalist, Windows 95, Carbon
`radius-xs`	4	Chip, badge, small button, tag
`radius-sm`	8	Default button, input field, tab, segmented control
`radius-md`	12	Card, dialog, sheet, container
`radius-lg`	16	Modal sheet, full-screen dialog, hero container
`radius-xl`	24	Floating action button, large sheet edge, ornament
`radius-full`	999	Pill button, avatar, chip with rounded ends

Defaults shown above match verge (Adwaita-based v0). Each preset in ui-style.kmd overrides these.

R1 — Role binding

Every container/control binds radius via a role, not a raw px:

/* ❌ */
button { border-radius: 8px; }

/* ✅ */
button { border-radius: var(--radius-sm); }

// ❌
BorderRadius.circular(8.0)

// ✅
BorderRadius.circular(KoderShape.of(context).sm)

R2 — Per-element default

Element family → typical role binding:

Family	Default	Notes
Surface (page bg)	none	Pages don't have corners
Container (card)	`radius-md`	Standard card frame
Container (sheet)	`radius-lg` on edges that meet screen, `radius-none` elsewhere
Control (button)	`radius-sm`	Most common control radius
Control (FAB)	`radius-xl` or `radius-full`	Pill/round
Control (chip)	`radius-xs` or `radius-full`	Per preset
Control (input)	`radius-sm`	Match buttons
Decoration (badge)	`radius-full`	Always pill
Content (image)	`radius-md`	Optional; depends on context
Modal/dialog	`radius-lg`	Distinct from regular cards

R3 — Per-preset variation (from ui-style.kmd)

The 35 ratified presets each define their own scale. Sample:

Preset	xs	sm	md	lg	xl
`verge` (default)	2	4	6	8	16
`material3`	4	8	12	16	24
`material2`	4	4	4	4	4
`gnome`	4	4	6	8	12
`windows_95`	0	0	0	0	0
`macos_sonoma`	6	6	10	14	20
`ios_cupertino`	10	10	14	20	28
`brutalist`	0	0	0	0	0
`glassmorphism`	8	12	16	24	32
`terminal_classic`	0	0	0	0	0
`carbon_ibm`	0	0	0	0	0
`shadcn`	4	6	8	10	12

Full table in themes/ui-style.kmd preset declarations.

R4 — Asymmetric shape

Sheets attached to screen edges use asymmetric radius — rounded only on edges that meet the screen.

.bottom-sheet {
  border-radius: var(--radius-lg) var(--radius-lg) 0 0;
}
.right-pane {
  border-radius: var(--radius-lg) 0 0 var(--radius-lg);
}

R5 — Shape consistency rules

Within one surface:

Mix at most 2 radii (excluding radius-full for pills)
Smaller children inside larger containers (button radius-sm inside card radius-md)
Never nest radius-full inside radius-none (visual jarring)

Across the whole app:

The preset defines THE shape language; deviation requires PR justification

R6 — Shape + motion

Shape can animate on state transitions per motion.kmd:

Expanding FAB: pill → rounded rectangle (radius shrinks)
Collapsing card: stays at constant radius (don't animate shape for state changes)
Modal entry: scales up, radius constant

@media (prefers-reduced-motion: reduce) disables shape transitions.

R7 — Forbidden patterns

❌ Per-corner control on standard widgets (border-radius: 8px 12px 4px 16px) — only asymmetric for sheet edges (R4)
❌ Negative shape (clip-path that cuts corners INWARD) — confusing
❌ Non-token radius values in widget code (use role binding)
❌ Animating radius repeatedly (looping shape morph) — distracting

Cross-link

ui-style.kmd — preset-specific radius scales
foundations/elements.kmd — element family ↔ radius binding
themes/motion.kmd — shape transitions during state changes

References

specs/themes/ui-style.kmd
specs/foundations/elements.kmd