Hero Cosmic
The cosmic landing hero: a full-height gradient surface carrying a twinkling starfield, shooting stars and meteors behind an eyebrow / headline / tagline / two-CTA column. A preset, not a kit — pass copy and CTAs and the decorative layer is already wired.
Preview
Rendered from the story the storybook (a11y) CI gate runs axe against — the preview can't show something that hasn't been verified.
Install
Two equivalent paths — the URL works in any shadcn-CLI setup; the alias works once you've registered @interlace in your components.json.
npx shadcn@latest add https://ds.interlace.tools/r/hero-cosmic.jsonnpx shadcn@latest add @interlace/hero-cosmicBehavior
What this component does — the keyboard path, the measured colour, the text equivalent and the states it can be in. Every figure below is read out of the test or the source that enforces it by scripts/build-behavior-map.mjs, so nothing here can outlive the gate that keeps it true.
Measured contrast
packages/ui/__tests__/theme-contract-lock.test.ts ↗Every semantic colour pair this component's own source uses, measured against the shipped hexes in all 4 theme × scheme combinations. The tightest is primary on background at 8.39:1 (harbor · light), against a floor of 3:1.
| Pair | interlacelight | interlacedark | harborlight | harbordark | Floor |
|---|---|---|---|---|---|
| primary on backgroundprimary tint on the page surface | 8.80:1 | 11.79:1 | 8.39:1 | 10.03:1 | 3.0:1SC 1.4.11 |
| primary on cardprimary tint inside a card | 8.80:1 | 10.92:1 | 8.86:1 | 9.10:1 | 3.0:1SC 1.4.11 |
| hero-foreground on hero-surfacecosmic hero copy | 16.83:1 | 16.83:1 | 15.76:1 | 15.76:1 | 4.5:1SC 1.4.3 |
Text pairs are held to 4.5:1 (WCAG 2.2 SC 1.4.3); borders, rings and chart axes to 3:1 (SC 1.4.11 non-text). Bold is the worst cell in the row — the one a brand fork has to keep an eye on.
Runtime contract
packages/ui/vitest.config.ts ↗Where it renders, how narrow it survives, and whether its lines are inside the coverage gate — three answers a consumer needs before the paste, not after the bug.
- Render boundary
'use client'Hydrates. It brings JavaScript to any route that imports it — put the boundary here, not at the page.
- Minimum viewport
MIN_VIEWPORT = 320Declared, not assumed. Below 320 CSS px the preflight contract draws a dev-mode outline — how to switch it on.
- Coverage gate
not in the gateThe 100% gate currently covers
src/charts/**/*.{ts,tsx}andsrc/lib/**/*.{ts,tsx}andsrc/primitives/{button-variants,data-state-model,meter-scale,skeleton-variants}.tsandsrc/primitives/{alert,aspect-ratio,avatar,badge,box,breadcrumb,button,callout,card,checkbox,container,data-state,focus-ring,grade-badge,grid,input,label,meter,pagination,published-date,reading-time,section,section-boundary,separator,skip-link,stack,stat-strip,tag,textarea,typography,visually-hidden}.tsx. This file is outside it — the glob widens in phase 7.2.
History
This component is at v1.4.0, first shipped in @interlace/ui 1.0.0. The version is stamped as a banner into the file the install writes, so the copy in your tree says which one you have — compare it with the number above before deciding whether to re-run the install.
No release note names this component yet. It shipped with the release above and has not changed since — see the full changelog for what moved elsewhere in the DS.
Import
2 named exports — pull the parts you need.
import { HeroCosmic, MIN_VIEWPORT } from '@/components/ui/patterns/hero-cosmic';Anatomy
Extracted from the primitive's JSDoc header. The source is the only documentation that can't drift.
HeroCosmic (div — data-slot="hero-cosmic", min-viewport 320)
└─ div (min-h-screen gradient, text-hero-foreground)
├─ div aria-hidden (data-slot="hero-cosmic-effects")
│ ├─ StarsBackground (canvas)
│ ├─ ShootingStars (svg)
│ └─ Meteors (CSS-animated spans)
└─ Container size=content (data-slot="hero-cosmic-body")
├─ eyebrow / h1 / tagline
├─ actions (primaryCta + secondaryCta)
└─ footerAPI reference
Parsed from the type declarations in the source — the same file the install writes into your tree, so this table can't drift from the component you get.
HeroCosmicProps
Also accepts every <div> attribute.
| Prop | Type | Description |
|---|---|---|
| eyebrow | React.ReactNode | Eyebrow content rendered above the headline (e.g. a trust chip). |
| headline* | React.ReactNode | Main headline. Pass JSX (`<>foo<br/>bar</>`) for multi-line headlines with gradient spans. |
| tagline | React.ReactNode | Sub-headline / tagline. |
| primaryCta | HeroCosmicCTA | Primary CTA. |
| secondaryCta | HeroCosmicCTA | Secondary CTA. |
| footer | React.ReactNode | Additional content rendered below CTAs (e.g. trust badges). |
| effects | HeroCosmicEffects | Tuning knobs for the decorative starfield. Colours are NOT part of this bag — they come from the `--hero-*` brand tokens so the effect can't drift from the palette. @default {} |
Accessibility
Every story for this component is rendered headlessly and checked with axe-core (wcag2aa, wcag22aa, best-practice, ACT) on every PR. That gate has no continue-on-error, so what ships has zero known violations.
What follows is what static analysis can see. Axe cannot press a key and never sees an overlay open, so the operable-without-a-mouse claim lives in Behavior instead, where the keyboard path is replayed step by step.
- Focus + keyboard behaviour
- Native element semantics — no interaction layer to get wrong.
- Focus ring (WCAG 2.2 SC 2.4.13)
- Not focusable — no focus indicator required.
- Reduced motion
- Animation is gated on prefers-reduced-motion.
- ARIA in the source
- None — semantics come from the element or the Base UI primitive rather than hand-written ARIA.
Examples
3 more states from the same story file.
R-rule compliance
Every primitive in @interlace/ui models to the portable 26-rule floor enforced by the componentApi ESLint preset. The cells below pin exactly where each rule applies in this file.
| Rule | Concept | Where |
|---|---|---|
| R4 | Extends native el | `Omit<React.ComponentProps<'div'>, 'children'\ |
| R5 | testid required, no default | `'data-testid': string` + derived part ids |
| R6 | data-slot on every part | `hero-cosmic` / `-effects` / `-headline` / `-cta` / … |
| R7 | className + rest + ref | `cn(...)`, `{...props}`, `ref` on the root |
| R10 | Composition seam | `HeroCosmicCTA.render` clones any element as the button |
| R19 | Tokens only | effect colours resolve from `--hero-*` — no hex here |
| R21 | Layout primitive | `<Container size="content">`, not open-coded `mx-auto` |
| R23 | CLS=0 | effects are `absolute` + `aria-hidden`; copy never moves |
| R25 | Client component | canvas + `getComputedStyle` need the DOM |
Minimum viewport
This primitive declares MIN_VIEWPORT = 320 CSS px (DESIGN_PRINCIPLES #14). When mounted in a container narrower than this, the preflight contract draws a dev-mode outline so the regression is visible during local development.
<body data-interlace-dev>...</body>
Add the data-interlace-dev attribute to the body in development builds only — preflight then outlines any primitive whose container is below its declared data-min-viewport.
Dependencies
- Base UI primitive
- Native / no Base UI dependency
- Lucide icons
- none
- NPM dependencies
- none
- Registry dependencies
Source
The full implementation — components/ui/patterns/hero-cosmic.tsx once installed.
'use client';
import * as React from 'react';
// @interlace/hero-cosmic v1.4.0 — Interlace design system.
// Docs, props and live preview: https://ds.interlace.tools/c/hero-cosmic
// What changed since: https://ds.interlace.tools/c/hero-cosmic#history
// Generated banner — keep it, the upgrade diff reads this version.
/**
* @interlace/ui — HeroCosmic
*
* The cosmic landing hero: a full-height gradient surface carrying a twinkling
* starfield, shooting stars and meteors behind an eyebrow / headline / tagline
* / two-CTA column. A preset, not a kit — pass copy and CTAs and the decorative
* layer is already wired.
*
* ## Anatomy
*
* HeroCosmic (div — data-slot="hero-cosmic", min-viewport 320)
…323 more lines…Registry JSON
The raw registry record — what the shadcn CLI fetches.