DesignMD

version: alpha name: Resend description: | Resend's marketing surfaces sit on a near-pure black canvas with off-white text and a single signature color — the deep editorial-serif Domaine Display headline mark — that gives an otherwise utilitarian developer-tool brand its print-magazine confidence. The system pairs Domaine Display (oversized 76px–96px serif, ss01/ss04/ss11 features on) with ABC Favorit for body and Inter for UI. Surfaces rely on subtle 6–9% opacity gradient glows, hairline 1px borders made from translucent white, and a strict rounded-12px container vocabulary. There is no decorative chrome — just type, code, and atmospheric depth.

colors: primary: "#fcfdff" primary-on: "#000000" ink: "#fcfdff" body: "rgba(252,253,255,0.86)" charcoal: "rgba(252,253,255,0.7)" mute: "#a1a4a5" ash: "#888e90" stone: "#464a4d" on-light: "#000000" on-light-mute: "rgba(0,0,51,0.7)" canvas: "#000000" surface-card: "#0a0a0c" surface-elevated: "#101012" surface-deep: "#06060a" hairline: "rgba(255,255,255,0.06)" hairline-strong: "rgba(255,255,255,0.14)" divider-soft: "rgba(255,255,255,0.04)" accent-orange: "#ff801f" accent-orange-glow: "rgba(255,89,0,0.22)" accent-yellow: "#ffc53d" accent-blue: "#3b9eff" accent-blue-glow: "rgba(0,117,255,0.34)" accent-green: "#11ff99" accent-green-glow: "rgba(34,255,153,0.18)" accent-red: "#ff2047" accent-red-glow: "rgba(255,32,71,0.34)" link: "#3b9eff" surface-light: "#f1f7fe"

typography: display-xxl: fontFamily: Domaine Display fontSize: 96px fontWeight: 400 lineHeight: 1.0 letterSpacing: -0.96px fontFeature: "ss01, ss04, ss11" display-xl: fontFamily: Domaine Display fontSize: 76.8px fontWeight: 400 lineHeight: 1.0 letterSpacing: -0.768px fontFeature: "ss01, ss04, ss11" display-lg: fontFamily: ABC Favorit fontSize: 56px fontWeight: 400 lineHeight: 1.2 letterSpacing: -2.8px fontFeature: "ss01, ss04, ss11" heading-md: fontFamily: Inter fontSize: 24px fontWeight: 500 lineHeight: 1.5 letterSpacing: -0.4px heading-sm: fontFamily: Inter fontSize: 20px fontWeight: 500 lineHeight: 1.3 letterSpacing: -0.3px subtitle: fontFamily: ABC Favorit fontSize: 20px fontWeight: 400 lineHeight: 1.3 fontFeature: "ss01, ss04, ss11" body-lg: fontFamily: Inter fontSize: 18px fontWeight: 400 lineHeight: 1.5 body-md: fontFamily: ABC Favorit fontSize: 16px fontWeight: 400 lineHeight: 1.5 letterSpacing: -0.8px fontFeature: "ss01, ss04, ss11" body-sm: fontFamily: Inter fontSize: 14px fontWeight: 400 lineHeight: 1.43 button-md: fontFamily: Inter fontSize: 14px fontWeight: 500 lineHeight: 1.43 button-sm: fontFamily: ABC Favorit fontSize: 14px fontWeight: 500 lineHeight: 1.43 letterSpacing: 0.35px fontFeature: "ss01, ss03, ss04" caption: fontFamily: Inter fontSize: 12px fontWeight: 400 lineHeight: 1.5 caption-emph: fontFamily: Helvetica fontSize: 14px fontWeight: 600 lineHeight: 1.0 code-md: fontFamily: Geist Mono fontSize: 13px fontWeight: 400 lineHeight: 1.6

rounded: none: 0px xs: 4px sm: 6px md: 8px lg: 12px xl: 16px full: 9999px

spacing: xxs: 2px xs: 4px sm: 8px md: 12px lg: 16px xl: 24px xxl: 32px xxxl: 48px section: 96px band: 128px

components: button-primary: backgroundColor: "{colors.primary}" textColor: "{colors.primary-on}" typography: "{typography.button-md}" rounded: "{rounded.md}" padding: 8px 16px height: 36px button-primary-pressed: backgroundColor: "{colors.surface-light}" textColor: "{colors.primary-on}" typography: "{typography.button-md}" rounded: "{rounded.md}" button-ghost: backgroundColor: "{colors.surface-elevated}" textColor: "{colors.ink}" typography: "{typography.button-md}" rounded: "{rounded.md}" padding: 8px 16px height: 36px button-outline: backgroundColor: "{colors.canvas}" textColor: "{colors.ink}" typography: "{typography.button-md}" rounded: "{rounded.md}" padding: 7px 15px height: 36px text-input: backgroundColor: "{colors.surface-card}" textColor: "{colors.ink}" typography: "{typography.body-sm}" rounded: "{rounded.md}" padding: 10px 14px height: 40px hero-stripe: backgroundColor: "{colors.canvas}" textColor: "{colors.ink}" typography: "{typography.display-xxl}" rounded: "{rounded.none}" padding: 96px 32px feature-card: backgroundColor: "{colors.surface-card}" textColor: "{colors.ink}" typography: "{typography.body-md}" rounded: "{rounded.lg}" padding: 32px feature-card-bordered: backgroundColor: "{colors.surface-card}" textColor: "{colors.ink}" typography: "{typography.body-md}" rounded: "{rounded.lg}" padding: 32px pricing-tier: backgroundColor: "{colors.surface-card}" textColor: "{colors.ink}" typography: "{typography.body-md}" rounded: "{rounded.lg}" padding: 32px pricing-tier-featured: backgroundColor: "{colors.surface-elevated}" textColor: "{colors.ink}" typography: "{typography.body-md}" rounded: "{rounded.lg}" padding: 32px code-window: backgroundColor: "{colors.surface-deep}" textColor: "{colors.body}" typography: "{typography.code-md}" rounded: "{rounded.lg}" padding: 24px code-tab: backgroundColor: "{colors.surface-card}" textColor: "{colors.charcoal}" typography: "{typography.code-md}" rounded: "{rounded.sm}" padding: 6px 12px email-mockup: backgroundColor: "{colors.surface-card}" textColor: "{colors.ink}" typography: "{typography.body-md}" rounded: "{rounded.lg}" padding: 0 badge-pill: backgroundColor: "{colors.surface-elevated}" textColor: "{colors.body}" typography: "{typography.caption}" rounded: "{rounded.full}" padding: 4px 10px status-dot: backgroundColor: "{colors.accent-green}" rounded: "{rounded.full}" size: 8px nav-bar: backgroundColor: "{colors.canvas}" textColor: "{colors.body}" typography: "{typography.button-sm}" rounded: "{rounded.none}" height: 64px sub-nav-pill: backgroundColor: "{colors.surface-elevated}" textColor: "{colors.body}" typography: "{typography.button-sm}" rounded: "{rounded.full}" padding: 6px 14px contributor-avatar: backgroundColor: "{colors.surface-card}" rounded: "{rounded.full}" size: 32px footer: backgroundColor: "{colors.canvas}" textColor: "{colors.charcoal}" typography: "{typography.body-sm}" rounded: "{rounded.none}" padding: 64px 32px

Overview

Resend looks like a developer tool with the typography of an editorial. Every page opens on {colors.canvas} (#000000), and the loudest element on the canvas is not a button or a brand stamp — it's a 96px Domaine Display serif headline ("Email for developers", "Email reimagined") with the ss01 / ss04 / ss11 stylistic alternates engaged. That single typographic decision sets the brand tone: confident, considered, slightly literary, and priced on quality rather than novelty.

The supporting cast is technical. Body copy switches to ABC Favorit for marketing prose and Inter for UI labels, while code blocks render in Geist Mono inside {component.code-window} shells with hairline traffic- light dots. Surface depth is built almost entirely from translucent white — 6% borders, 14% strong borders, 4% dividers — over a deep {colors.surface-deep} layer that sits just below the canvas black. There are no gradients painted across full bands, just soft atmospheric glows (orange, blue, green, red, yellow) anchored at the top of select sections, all at low opacity.

Page rhythm cycles in a single dark register: hero stripe → atmospheric section → code window section → email mockup section → pricing or feature grid → black footer. The brand never warms to a light surface; even secondary email mockups are rendered as compact white cards inside the dark canvas, framed like print insets in a black-bordered magazine page.

Key Characteristics:

Pure black canvas ({colors.canvas} — #000000) on every public page; off-white text ({colors.ink} — #fcfdff) carries the full read.
A serif-led type system: Domaine Display at 76–96px for hero headlines, ABC Favorit for marketing body, Inter for UI, Geist Mono for code.
Six accent glow colours used only as low-opacity atmospheric washes ({colors.accent-orange}, {colors.accent-blue}, {colors.accent-green}, {colors.accent-red}, {colors.accent-yellow}) — never as buttons or solid surfaces.
Strict container vocabulary: {rounded.lg} (12px) for feature cards, code wells, and email mockups; {rounded.md} (8px) for buttons; {rounded.full} for pills and avatars.
Translucent white borders ({colors.hairline} 6% / {colors.hairline-strong} 14%) replace shadows entirely — the system has no traditional drop-shadow elevation language.
{component.button-primary} is a small white rectangle with black text — counterintuitive contrast that becomes the page's brightest pixel and works as a single visual anchor.

Colors

Brand & Accent

Primary White ({colors.primary} — #fcfdff): the brand's de facto accent. Reserved for {component.button-primary} (white pill on black canvas), Domaine display headlines, and the active text colour. White is the loudest possible colour on this canvas — that's the signature.
Primary On ({colors.primary-on} — #000000): label colour on top of {colors.primary} surfaces. Black text on white pill is the brand's CTA pattern.
Surface Light ({colors.surface-light} — #f1f7fe): a subtle blue-tinted off-white used as the active/pressed state of {component.button-primary}.

Surface

Canvas ({colors.canvas} — #000000): the default page background. True black, never near-black.
Surface Card ({colors.surface-card} — #0a0a0c): the standard inset card surface, just lighter than canvas to register a step up in elevation.
Surface Elevated ({colors.surface-elevated} — #101012): a second elevation step used on featured pricing tiers and ghost button surfaces.
Surface Deep ({colors.surface-deep} — #06060a): code window background — slightly cooler and darker than the canvas itself, suggesting depth via temperature.
Hairline ({colors.hairline} — rgba(255,255,255,0.06)): the soft 1px translucent-white divider used between rows and around feature cards.
Hairline Strong ({colors.hairline-strong} — rgba(255,255,255,0.14)): the structural 1px border on cards, code wells, and form inputs.
Divider Soft ({colors.divider-soft} — rgba(255,255,255,0.04)): low-contrast dividers between footer columns.

Text

Ink ({colors.ink} — #fcfdff): primary text colour on the dark canvas. Faintly blue-cool to feel like printed paper rather than pure white pop.
Body ({colors.body} — rgba(252,253,255,0.86)): long-form body text where pure ink would feel too sharp.
Charcoal ({colors.charcoal} — rgba(252,253,255,0.7)): captions, secondary nav labels.
Mute ({colors.mute} — #a1a4a5): supporting text and inactive labels.
Ash ({colors.ash} — #888e90): tertiary text, footer copy.
Stone ({colors.stone} — #464a4d): disabled foreground.
On-Light ({colors.on-light} — #000000): label colour inside the rare email-mockup white cards.
On-Light Mute ({colors.on-light-mute} — rgba(0,0,51,0.7)): secondary text inside email mockups.

Semantic

Accent Orange ({colors.accent-orange} — #ff801f) + glow ({colors.accent-orange-glow} — rgba(255,89,0,0.22)): atmospheric warm wash anchored to "Email reimagined" / customer story sections. Solid orange never appears as a button or surface — only the glow.
Accent Yellow ({colors.accent-yellow} — #ffc53d): used in inline highlight strokes and "first-class developer experience" key callouts.
Accent Blue ({colors.accent-blue} — #3b9eff) + glow ({colors.accent-blue-glow} — rgba(0,117,255,0.34)): inline link colour and the cool atmospheric wash on the "Integrate this weekend" section.
Accent Green ({colors.accent-green} — #11ff99) + glow ({colors.accent-green-glow} — rgba(34,255,153,0.18)): success status dots and the "delivery confirmed" feature glow.
Accent Red ({colors.accent-red} — #ff2047) + glow ({colors.accent-red-glow} — rgba(255,32,71,0.34)): inline error red and the "reach humans, not spam folders" attention wash.
Link ({colors.link} — #3b9eff): inline link colour — same as accent blue.

Typography

Font Family

Resend ships a four-family stack:

Domaine Display — proprietary editorial serif used exclusively for hero headlines at 76px+, with ss01 / ss04 / ss11 stylistic sets engaged for a slightly tighter, more print-magazine look.
ABC Favorit — proprietary humanist sans-serif used for marketing body copy, hero subtitles, and pill labels. Carries ss01 / ss03 / ss04 features for tabular figures and alternate glyphs.
Inter — open-source sans-serif used for UI: button labels, captions, card body text, nav links.
Geist Mono — open-source monospace used in code wells.

When proprietary families cannot be licensed, Söhne or Tiempos Headline stand in for Domaine Display, and Geist or Inter Tight can replace ABC Favorit. Inter and Geist Mono are open-source and should be used directly.

Hierarchy

Token	Size	Weight	Line Height	Letter Spacing	Use
`{typography.display-xxl}`	96px	400	1.0	-0.96px	Home hero ("Email for developers"). One per page.
`{typography.display-xl}`	76.8px	400	1.0	-0.768px	Section openers ("Email reimagined", "Available today").
`{typography.display-lg}`	56px	400	1.2	-2.8px	ABC Favorit display sub-titles.
`{typography.heading-md}`	24px	500	1.5	-0.4px	Card titles, section sub-titles.
`{typography.heading-sm}`	20px	500	1.3	-0.3px	List headers.
`{typography.subtitle}`	20px	400	1.3	0	Hero subtitles.
`{typography.body-lg}`	18px	400	1.5	0	Marketing prose.
`{typography.body-md}`	16px	400	1.5	-0.8px	ABC Favorit body.
`{typography.body-sm}`	14px	400	1.43	0	Captions, metadata.
`{typography.button-md}`	14px	500	1.43	0	Default button label.
`{typography.button-sm}`	14px	500	1.43	0.35px	Pill labels, inline links.
`{typography.caption}`	12px	400	1.5	0	Footer disclosure, copyright.
`{typography.caption-emph}`	14px	600	1.0	0	Emphatic small caption — Helvetica fallback.
`{typography.code-md}`	13px	400	1.6	0	Code blocks, inline code.

Principles

Display sizes always run at lineHeight: 1.0 with negative letter-spacing — the Domaine Display headlines pack into solid typographic blocks rather than open prose lines.
Body weight stays at 400 across {typography.body-lg} and {typography.body-md}. The serif/sans family change carries hierarchy, not weight bumps.
ABC Favorit always runs with ss01 / ss04 / ss11 engaged; Inter never carries OpenType features. Code in Geist Mono never carries ligatures.
Inline links use {typography.button-sm} with positive letter-spacing (0.35px) and ABC Favorit — the small spacing nudge gives interactive prose its precision.

Note on Font Substitutes

When Domaine Display is unavailable, clamp lineHeight to 1.0 explicitly and apply font-feature-settings: "ss01", "liga" on the substitute serif to mimic the alternate glyphs. Söhne or Tiempos Headline will read closest. ABC Favorit substitutes (Geist, Inter Tight) typically default to looser tracking — apply -0.5% letter-spacing on body sizes to compensate.

Layout

Spacing System

Base unit: 4px, with the working scale on multiples of 4 / 8 / 16.
Tokens: {spacing.xxs} 2px · {spacing.xs} 4px · {spacing.sm} 8px · {spacing.md} 12px · {spacing.lg} 16px · {spacing.xl} 24px · {spacing.xxl} 32px · {spacing.xxxl} 48px · {spacing.section} 96px · {spacing.band} 128px.
Section padding: {spacing.section} (96px) vertical between bands; {spacing.band} (128px) on the hero stripe and closing footer transition.
Card internal padding: {spacing.xxl} (32px) on {component.feature-card}, {component.pricing-tier}, and {component.code-window}.

Grid & Container

Max content width ≈ 1200px on body sections.
Feature grid: 3 columns at desktop, 2 at tablet, 1 at mobile.
Pricing: 3-tier grid centred at desktop; centre tier promotes to {component.pricing-tier-featured} (one-step-elevated surface).
Code-story splits: a 2-up split — narrative copy left, {component.code-window} right — collapsing to stacked at < 1024px.
Email mockup band: a single white card (640px max width) centred in the dark canvas with generous vertical padding to read like a print magazine inset.

Whitespace Philosophy

Whitespace is editorial and generous — full-bleed sections breathe at 96–128px so Domaine Display headlines have room to register at scale.
Inside cards, padding stays at 32px so feature copy and code wells have a consistent rhythm with the outer grid.
Hairline {colors.hairline} and {colors.hairline-strong} carry the role drop shadows would in a brighter system; the dark canvas suppresses traditional shadow depth entirely.

Elevation & Depth

Level	Treatment	Use
0 — flat	No shadow, no border	Default canvas, full-bleed bands.
1 — surface card	`{colors.surface-card}` (`#0a0a0c`) + 1px `{colors.hairline-strong}`	Feature cards, pricing tiers, form inputs.
2 — elevated	`{colors.surface-elevated}` (`#101012`) + 1px `{colors.hairline-strong}`	Featured pricing tier, ghost button.
3 — code well	`{colors.surface-deep}` (`#06060a`) + 1px `{colors.hairline-strong}`	Code window, terminal shells.
4 — atmospheric glow	Low-opacity radial gradient (`{colors.accent-*-glow}`) anchored at section top	Section openers ("Integrate this weekend", "Email reimagined").

The system has no traditional drop shadow language. Every surface either gets a translucent-white hairline border or sits inside an atmospheric glow. The dark canvas absorbs shadow naturally; surfaces register depth via temperature and luminance shifts rather than blur.

Decorative Depth

Atmospheric section glows — six accent colours each with a paired glow token (orange, yellow, blue, green, red, plus a deep slate for "everything in your context"). Each section opens with a single radial wash anchored at the top edge of the section, falling off to canvas black within ~600px vertical distance. Never two glows in the same section.
Email card insets — the "Beyond experience" mockup band lifts a single white email card off the black canvas, giving it the only true light-on-dark contrast in the system. The card uses no shadow; the contrast itself is the elevation.
Code window traffic lights — {component.code-window} shells include a row of three coloured dots (red {colors.accent-red}, yellow {colors.accent-yellow}, green {colors.accent-green}) at the top — the only place all three semantic colours appear together as solid surfaces.

Shapes

Border Radius Scale

Token	Value	Use
`{rounded.none}`	0px	Hero stripe, full-bleed bands, footer.
`{rounded.xs}`	4px	Inline tags inside code wells.
`{rounded.sm}`	6px	Code tabs, mid-size chips.
`{rounded.md}`	8px	Buttons, form inputs.
`{rounded.lg}`	12px	Feature cards, pricing tiers, code wells, email mockups.
`{rounded.xl}`	16px	Larger feature panels.
`{rounded.full}`	9999px	Pills, status dots, contributor avatars.

Photography Geometry

The system uses almost no photography. Visual interest comes from typography + atmospheric glows + code wells + the white email-card insets.
When portraits appear (testimonial avatars), they are circular ({rounded.full}) at 32px, sitting inline with body copy.
Email mockup cards run at 4:5 portrait aspect with {rounded.lg} corners.

Components

Buttons

button-primary — white CTA

Background {colors.primary}, label {colors.primary-on}, type {typography.button-md}, padding 8px 16px, rounded: {rounded.md}, height 36px.
The brightest pixel on the canvas. Used for "Get started", "Sign up", "Try Resend".
Pressed state lives in button-primary-pressed (background {colors.surface-light}).

button-ghost — translucent CTA

Background {colors.surface-elevated}, label {colors.ink}, 1px {colors.hairline-strong}, type {typography.button-md}, rounded: {rounded.md}, height 36px.
Equal-weight secondary action paired with {component.button-primary}.

button-outline — outlined CTA

Background {colors.canvas}, label {colors.ink}, 1px {colors.hairline-strong}, type {typography.button-md}, rounded: {rounded.md}, height 36px.
Tertiary action; appears on its own next to inline links.

Cards & Containers

hero-stripe — full-bleed hero

Background {colors.canvas}, text {colors.ink}, type {typography.display-xxl} for the headline, padding 96px 32px, rounded: {rounded.none}.
Used only on the home page hero band; carries the 96px Domaine Display headline and a single {component.button-primary} CTA. No photography, no atmospheric glow inside the hero itself — the glow appears on the section that follows.

feature-card — feature highlight card

Background {colors.surface-card}, text {colors.ink}, type {typography.body-md}, rounded: {rounded.lg}, padding {spacing.xxl} (32px).
Used in the home grid: "Despite emails using React", "So beyond editing", etc. No outline by default — relies on canvas black contrast.

feature-card-bordered — outlined feature card

Background {colors.surface-card}, text {colors.ink}, 1px {colors.hairline-strong}, type {typography.body-md}, rounded: {rounded.lg}, padding {spacing.xxl}.
Used when feature cards sit close together and need explicit separation.

pricing-tier — pricing tier card

Background {colors.surface-card}, text {colors.ink}, 1px {colors.hairline-strong}, type {typography.body-md}, rounded: {rounded.lg}, padding {spacing.xxl} (32px).
Tier name in {typography.heading-md} + price in {typography.display-lg} (ABC Favorit, 56px).

pricing-tier-featured — recommended tier

Background {colors.surface-elevated}, text {colors.ink}, 1px {colors.hairline-strong}, type {typography.body-md}, rounded: {rounded.lg}, padding {spacing.xxl}.
Centre tier elevated by surface luminance, not by colour.

code-window — code well

Background {colors.surface-deep}, text {colors.body}, type {typography.code-md}, 1px {colors.hairline-strong}, rounded: {rounded.lg}, padding {spacing.xl} (24px).
Includes a 3-dot traffic-light row at top using {colors.accent-red} / {colors.accent-yellow} / {colors.accent-green} for chrome, plus a tab strip below it.

code-tab — code language tab

Background {colors.surface-card}, text {colors.charcoal}, type {typography.code-md}, rounded: {rounded.sm}, padding 6px 12px.
Active tab bumps text to {colors.ink} and adds a subtle {colors.hairline-strong} underline.

email-mockup — email-card inset

Background {colors.surface-card} (or the rare #ffffff when rendered as a light-island inset), text {colors.ink} (or {colors.on-light} for white insets), type {typography.body-md}, rounded: {rounded.lg}, padding 0.
Used in the "Beyond experience" band to demonstrate rendered email output.

Inputs & Forms

text-input — default input

Background {colors.surface-card}, text {colors.ink}, type {typography.body-sm}, 1px {colors.hairline-strong}, rounded: {rounded.md}, padding 10px 14px, height 40px.
Sign-up and waitlist email fields. Focus state thickens the border to {colors.ink} (no separate ring colour).

Navigation

nav-bar — top nav (desktop)

Background {colors.canvas}, text {colors.body}, type {typography.button-sm}, height 64px, single hairline {colors.hairline} bottom border.
Left: wordmark logo. Centre: top-level nav ("Features", "Pricing", "Docs", "Customers"). Right: "Sign in" link + {component.button-primary}.

nav-bar (mobile)

Same height 64px, collapses centre nav into a hamburger icon. Logo stays left, sign-in CTA stays right.

sub-nav-pill — pill-style sub-nav

Pill chips set in a horizontal row above content (e.g. on the customers index), {component.sub-nav-pill} styling.

Signature Components

badge-pill — neutral pill

Background {colors.surface-elevated}, text {colors.body}, type {typography.caption}, rounded: {rounded.full}, padding 4px 10px.
Inline tags ("New", "Beta", "v3.0") inside hero copy and customer story headers.

status-dot — status indicator

Background {colors.accent-green}, rounded: {rounded.full}, 8px square.
Inline indicator next to "Status: Operational" in the footer or system status references.

contributor-avatar — testimonial avatar

Background {colors.surface-card} placeholder, rounded: {rounded.full}, 32×32px.
Used inline with customer testimonials.

footer — global footer

Background {colors.canvas}, text {colors.charcoal}, type {typography.body-sm}, rounded: {rounded.none}, padding 64px 32px.
Multi-column quick-links grid above a single-line copyright row separated by {colors.divider-soft}.

Do's and Don'ts

Do

Use {colors.canvas} (true black) as the default page background. Every public page lives here.
Reserve {component.button-primary} (white pill) as the only solid bright surface. One per viewport at most.
Set hero headlines in Domaine Display at 76–96px with lineHeight: 1.0 and ss01 / ss04 / ss11 features engaged.
Use ABC Favorit for marketing body, Inter for UI labels, Geist Mono for code. Keep the lanes strict.
Build elevation from translucent-white hairlines, not drop shadows.
Use {colors.accent-*-glow} tokens as low-opacity radial atmospheric washes — never as solid surfaces.
Set buttons and inputs to {rounded.md} (8px); cards and code wells to {rounded.lg} (12px); pills and avatars to {rounded.full}.
Use the white email-mockup inset sparingly — it's the only deliberately-light surface and should feel like a print pull-quote.

Don't

Don't use a near-black canvas. The brand sits on #000000, not #0a0a0a.
Don't apply solid colour to atmospheric accent tokens. {colors.accent-orange} is for inline highlights only — its glow form is for backdrops.
Don't add drop shadows to feature cards or code wells. Translucent white borders carry depth on this canvas.
Don't bump body weight to 600 for emphasis. Use family change (Inter → ABC Favorit → Domaine Display) instead.
Don't render code outside {component.code-window} — even small inline code uses Geist Mono and a {colors.surface-card} background.
Don't loosen Domaine Display lineHeight past 1.0. Tight stacking is structural to the brand.
Don't introduce a secondary brand accent. White is the brand on black — accents are atmospheric only.
Don't bring photography front-and-centre. The brand reads as type-and-code, not photography-led.

Responsive Behavior

Breakpoints

Name	Width	Key Changes
Desktop XL	≥ 1440px	Full max-width 1200 body, 3-up feature grid, side-by-side code-story splits.
Desktop	1280–1439px	Container shrinks; xl side padding.
Tablet Large	1024–1279px	Feature grid stays 3-up, code-story remains 2-up.
Tablet	768–1023px	Feature grid 2-up, code-story stacks (narrative on top), pricing stacks vertically.
Mobile Large	426–767px	Feature grid 1-up; nav collapses to hamburger; hero `{typography.display-xxl}` clamps to 56px.
Mobile	≤ 425px	All grids 1-up, hero clamps to 44px, section padding `{spacing.section}` collapses to 64px.

Touch Targets

All buttons ship at minimum 36px tall on desktop, scaling to 44px on mobile via padding adjustment. WCAG AAA met on mobile.
{component.text-input} is 40px tall — comfortable but not large. Mobile scales to 48px via padding.
{component.sub-nav-pill} stays at 36px on desktop, 40px on mobile.

Collapsing Strategy

Top-level nav collapses to hamburger at < 1024px; the wordmark and {component.button-primary} stay anchored.
Hero {typography.display-xxl} clamps: 96px → 76px → 56px → 44px across the breakpoint ladder.
Pricing 3-up stacks vertically at < 1024px with the featured tier remaining centre-stacked.
Code-story splits switch from side-by-side to stacked at < 1024px, code well always second.
Atmospheric glows scale with section width but maintain the same opacity — they fade naturally at small viewports.

Image Behavior

Email mockup cards reflow at 1:1 aspect on mobile to remain readable.
Atmospheric glows are CSS gradients — no asset cost, no breakpoint variation.
Customer testimonial avatars stay 32px circular regardless of breakpoint.

Iteration Guide

Focus on ONE component at a time. Most surfaces share {colors.surface-card} or {colors.surface-elevated} with {rounded.lg} — only the role-specific tokens ({colors.primary}, {component.code-window}) shift between variants.
Reference component names and tokens directly ({colors.primary}, {component.button-primary-pressed}, {rounded.lg}) — do not paraphrase.
Run npx @google/design.md lint DESIGN.md after edits; orphaned-tokens warnings will catch unused entries.
Add new variants as separate entries (-pressed, -featured, -disabled) — do not bury them in prose.
Default body type to {typography.body-md}; reach for {typography.subtitle} only on hero subtitles.
Keep {colors.primary} (white) scarce — if more than one solid white surface appears per viewport, ask whether one should drop to {component.button-ghost} instead.

Known Gaps

Pressed/active visual states are documented only for button-primary-pressed; other components rely on the default focus-ring (browser default) for interactive feedback.
Logged-in dashboard surfaces (API keys, sending logs, audience management) are out of scope; only the public marketing canvas is documented.
Email-template editor surfaces (a key product feature) are not extracted — those live behind authentication.
The atmospheric glow rendering uses CSS radial gradients; exact stops and angles vary per section and are not standardised as tokens — render per section-specific design judgment.