Halogen

v17 · published

Engineered calm - cold light on graphite, precise to the pixel.

precisegraphiteluminousrestrained

Halogen is a re-reading of the modern product-tool aesthetic: a near-black graphite canvas where almost nothing glows, so the few things that do feel deliberate. Color is rationed to a whisper - surfaces and borders are barely-there white films, text is a cool off-white at high contrast, and a single electric indigo carries every primary action. A humanist sans does the talking while a mono face stamps the technical details, echoing the engineering culture the source was built for. Motion is fast and restrained, riding one signature easing curve.

Open the playground →Fork it · design a page →

re-imagined from https://linear.app

Use in your project

Pull this design system into any project - it follows the system's tokens, recipes and rules. Run the commands yourself, or let your coding agent set it up and build.

1 · Authenticate

npx synthesisui@latest login

2 · Add this design system

npx synthesisui add halogen --version 17

3 · Import the tokens in your global CSS

@import "_synthesisui/ds/halogen/tokens.css";
@import "_synthesisui/ds/halogen/theme.css";

Ask your agent

Use the "Halogen" design system (slug: halogen) to: build the UI I describe next

First make sure it's installed: run `npx synthesisui add halogen` if `_synthesisui/ds/halogen/` isn't in the project yet.

Read these files first (highest authority first):
- _synthesisui/ds/halogen/rules.md - project rules for this system (if present); obey them above everything else
- _synthesisui/ds/halogen/philosophy.md - the mission, voice and principles (if present); let it shape every screen
- _synthesisui/ds/halogen/v17/GUIDE.md - how to apply the system, the recipes and the token vocabulary

Follow this contract (target framework: next):
- First check whether this refers to UI that already exists in the project. If it does, modify only what's needed and keep the rest intact and on-system. If it doesn't, build it new.
- Scope the markup with `data-ds="halogen"` (or rely on it at the app root).
- Style with the design system only: reuse the `.ds-*` recipe classes and the DS-backed Tailwind utilities (`bg-primary`, `text-foreground`, `p-md`, `rounded-lg`, `font-display`…). Never use raw hex/px outside the system's scale.
- Make sure `tokens.css` + `theme.css` are imported in the global CSS (see the GUIDE's "How to apply").
- Wire the behavior yourself (open/close, focus, routing) - the system ships the looks, not the JS.

Composition (make it look composed, not just correct):
- Cap page content with a max-width container and center it - this DS ships `max-w-app` for dashboards/wide UI and `max-w-prose` for text columns. Don't stretch content edge-to-edge.
- Give the page a complete, intentional layout: clear vertical rhythm, sensible density and grouped sections. Never leave a single thin row floating on an empty screen.

Deliver senior-level, production-quality code: clean structure, accessible (ARIA + keyboard), and responsive.

Paste into Claude Code, Cursor or any coding agent. From your project you can also run npx synthesisui use halogen "…".

Dependencies

What to install or load so the system renders at full fidelity - it ships token names and recipes, not the assets.

Web fonts - Inter Variable, Berkeley Mono
The system ships token names, not the fonts. Load them (Google Fonts, next/font or Fontsource) or type falls back to a generic family and loses the system's identity.
Icons - Lucidenpm i lucide-react
Components reference Lucide icon names. Install it (or swap in your own icon set) to render them.
Chartsnpm i recharts
Charts are themed through your series tokens, but you bring the rendering library (the gallery uses Recharts).

Color

Primitives and roles.

Named scales forged by the synthesis; semantic roles only ever point at them.

color.moss

400#4f9d76

500#3f8a66

color.rose

400#e0576a

500#cf3f54

color.veil

500#05070ab3

color.amber

400#c9973f

500#b3842f

color.blush

300#f9bfe9

400#f79ce0

500#ec6fd0

color.slate

50#ffffff

100#f7f8f8

200#e2e4e7

300#d0d6e0

400#8a8f98

500#62666d

600#383b3f

700#23252a

800#18191c

900#0f1011

950#08090a

color.indigo

300#a5b4ff

400#7c8cff

500#5b6cff

600#4453e6

700#3540b4

color.semantic - resolved live via CSS variables

info

{color.indigo.400}

faint

{color.slate.500}

muted

{color.slate.400}

scrim

{color.veil.500}

accent

{color.blush.400}

border

{color.slate.700}

canvas

{color.slate.950}

danger

{color.rose.400}

raised

{color.slate.800}

overlay

{color.slate.700}

primary

{color.indigo.500}

success

{color.moss.400}

surface

{color.slate.900}

warning

{color.amber.400}

foreground

{color.slate.100}

color.series - categorical data-viz palette (bg-series-*)

series-1

series-2

series-3

series-4

series-5

series-6

series-7

series-8

Foundations

Shape & depth.

Corner radius, spacing rhythm and elevation - the physical feel of the system.

radius

full

spacing

3xs0.25rem

2xs0.5rem

xs0.75rem

sm1rem

md1.5rem

lg2rem

xl3rem

2xl4rem

3xl6rem

shadow

glow

ring

Typography

The voice of the system.

Display: Inter Variable · Body: Inter Variable · Mono: Berkeley Mono

xsDesign, set free0.75rem / 1rem

smDesign, set free0.875rem / 1.5

baseDesign, set free1rem / 1.6

lgDesign, set free1.25rem / 1.4

xlDesign, set free1.5rem / 1.3

2xlDesign, set free2rem / 1.2

displayDesign, set free4rem / 1.05

Motion

How it breathes.

Every keyframe runs live below, dressed in the system's own colors - durations, easing curves and the interactions they power.

keyframes - 7 live

rise

blink

float

pulse

sheen

expand

slide-in

easings

standardease

outease-out

swiftcubic-bezier(0.25, 0.46, 0.45, 0.94)

durations

base · 200msfast · 120msslow · 320msambient · 3.5s

interaction patterns

enterentrance

Content rises a short distance as it fades in.

hoverhover-raise

Interactive surfaces brighten their ring on hover.

loopcursor-blink

The command-bar caret blinks with mechanical precision.

enterlist-stagger

Rows slide in from the left in quick succession.

loopambient-pulse

Status dots breathe at a calm, steady cadence.

pressunderline-grow

Active tab underline expands from the center.

Components · 44

Recipes, rendered live.

Every value below is a token reference resolved by the renderer - hover, toggle and switch tabs to feel the states. Bespoke components are rendered from their anatomy hint.

ds-badge

Mono-stamped label for technical metadata; accent variant uses the blush highlight.

intent

infoaccentdangerneutralsuccesswarning

ds-button

Compact, low-radius action. Primary carries the lone indigo; the rest stay in graphite films.

intent

ds-command-bar

bespoke · field

⌘K launcher - the product's front door.

ds-card

Graphite surface defined by a hairline ring rather than a border; raises on hover.

padding

Default

A card wearing this system.

None

A card wearing this system.

emphasis

Default

A card wearing this system.

Elevated

A card wearing this system.

ds-select

Field trigger that reveals a focus ring on interaction.

Choose an option

ds-input

Quiet field that reveals an indigo focus ring on interaction.

ds-avatar

Identity token - sized circle with initials or image.

size

MAMAMA

ds-link

bespoke · surface

Inline text link, for words inside sentences - the underline is the affordance, so it reads as a link without relying on colour alone. For standalone actions use button; for navigation chrome use navbar/sidebar items.

A surface wearing this system.

ds-kicker

bespoke · text

Mono uppercase eyebrow with wide tracking - the HUD microtype that labels a section ("01 · ECOSYSTEM"). Use above headings; data-tone="accent" for the highlighted variant.

tone

defaultaccent

ds-readout

bespoke · text

HUD data readout - a mono tabular value over a micro uppercase label ("42s · AVG RENDER"). The corner instrument of cinematic scenes; pair with the count-up hook for live-feeling numbers.

ValueLabel

ds-heading

bespoke · text

Display heading on the system's type scale - the display family at a semibold weight. Pick a `size` step (defaults to 2xl) so headings stay on-scale without hand-set styles.

size

lgxl2xldisplay

ds-text

bespoke · text

Body copy on the system's type scale. Pick a `size` step and a `tone`; defaults to base body text on the foreground color - so text stays on-system without hand-set styles.

size

xssmbaselg

tone

defaultmuted

ds-stack

bespoke · surface

Vertical layout primitive - a flex column with a token `gap` (defaults to md). Stack sections/cards without hand-set flex styles.

gap

A surface wearing this system.

align

A surface wearing this system.

ds-row

bespoke · surface

Horizontal layout primitive - a centered flex row with a token `gap` (defaults to sm). Compose toolbars/inline groups without hand-set flex styles.

gap

A surface wearing this system.

justify

A surface wearing this system.

align

A surface wearing this system.