git:20260403.74adb86 to git:20260404.129724c

- ## 1. Visual Theme & Atmosphere

-

- Resend's website is a dark, cinematic canvas that treats email infrastructure like a luxury product. The entire page is draped in pure black (`#000000`) with text that glows in near-white (`#f0f0f0`), creating a theater-like experience where content performs on a void stage. This isn't the typical developer-tool darkness — it's the controlled darkness of a photography gallery, where every element is lit with intention and nothing competes for attention.

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- The typography system is the star of the show. Three carefully chosen typefaces create a hierarchy that feels both editorial and technical: Domaine Display (a Klim Type Foundry serif) appears at massive 96px for hero headlines with barely-there line-height (1.00) and negative tracking (-0.96px), creating display text that feels like a magazine cover. ABC Favorit (by Dinamo) handles section headings with an even more aggressive letter-spacing (-2.8px at 56px), giving a compressed, engineered quality to mid-tier text. Inter takes over for body and UI, providing the clean readability that lets the display fonts shine. Commit Mono rounds out the family for code blocks.

-

- What makes Resend distinctive is its icy, blue-tinted border system. Instead of neutral gray borders, Resend uses `rgba(214, 235, 253, 0.19)` — a frosty, slightly blue-tinted line at 19% opacity that gives every container and divider a cold, crystalline quality against the black background. Combined with pill-shaped buttons (9999px radius), multi-color accent system (orange, green, blue, yellow, red — each with its own CSS variable scale), and OpenType stylistic sets (`"ss01"`, `"ss03"`, `"ss04"`, `"ss11"`), the result is a design system that feels premium, precise, and quietly confident.

-

- **Key Characteristics:**

- - Pure black background with near-white (`#f0f0f0`) text — theatrical, gallery-like darkness

- - Three-font hierarchy: Domaine Display (serif hero), ABC Favorit (geometric sections), Inter (body/UI)

- - Icy blue-tinted borders: `rgba(214, 235, 253, 0.19)` — every border has a cold, crystalline shimmer

- - Multi-color accent system: orange, green, blue, yellow, red — each with numbered CSS variable scales

- - Pill-shaped buttons and tags (9999px radius) with transparent backgrounds

- - OpenType stylistic sets (`"ss01"`, `"ss03"`, `"ss04"`, `"ss11"`) on display fonts

- - Commit Mono for code — monospace as a design element, not an afterthought

- - Whisper-level shadows using blue-tinted ring: `rgba(176, 199, 217, 0.145) 0px 0px 0px 1px`

-

- ## 2. Color Palette & Roles

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- ### Primary

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- - **Void Black** (`#000000`): Page background, the defining canvas color (95% opacity via `--color-black-12`)

- - **Near White** (`#f0f0f0`): Primary text, button text, high-contrast elements

- - **Pure White** (`#ffffff`): `--color-white`, maximum emphasis text, link highlights

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- ### Accent Scale — Orange

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- - **Orange 4** (`#ff5900`): `--color-orange-4`, at 22% opacity — subtle warm glow

- - **Orange 10** (`#ff801f`): `--color-orange-10`, primary orange accent — warm, energetic

- - **Orange 11** (`#ffa057`): `--color-orange-11`, lighter orange for secondary use

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- ### Accent Scale — Green

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- - **Green 3** (`#22ff99`): `--color-green-3`, at 12% opacity — faint emerald wash

- - **Green 4** (`#11ff99`): `--color-green-4`, at 18% opacity — success indicator glow

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- ### Accent Scale — Blue

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- - **Blue 4** (`#0075ff`): `--color-blue-4`, at 34% opacity — medium blue accent

- - **Blue 5** (`#0081fd`): `--color-blue-5`, at 42% opacity — stronger blue

- - **Blue 10** (`#3b9eff`): `--color-blue-10`, bright blue — links, interactive elements

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- ### Accent Scale — Other

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- - **Yellow 9** (`#ffc53d`): `--color-yellow-9`, warm gold for warnings or highlights

- - **Red 5** (`#ff2047`): `--color-red-5`, at 34% opacity — error states, destructive actions

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- ### Neutral Scale

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- - **Silver** (`#a1a4a5`): Secondary text, muted links, descriptions

- - **Dark Gray** (`#464a4d`): Tertiary text, de-emphasized content

- - **Mid Gray** (`#5c5c5c`): Hover states, subtle emphasis

- - **Medium Gray** (`#494949`): Quaternary text

- - **Light Gray** (`#f8f8f8`): Light mode surface (if applicable)

- - **Border Gray** (`#eaeaea`): Light context borders

- - **Edge Gray** (`#ececec`): Subtle borders on light surfaces

- - **Mist Gray** (`#dedfdf`): Light dividers

- - **Soft Gray** (`#e5e6e6`): Alternate light border

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- ### Surface & Overlay

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- - **Frost Primary** (`#fcfdff`): Primary color token (slight blue tint, 94% opacity)

- - **White Hover** (`rgba(255, 255, 255, 0.28)`): Button hover state on dark

- - **White 60%** (`oklab(0.999994 ... / 0.577)`): Semi-transparent white for muted text

- - **White 64%** (`oklab(0.999994 ... / 0.642)`): Slightly brighter semi-transparent white

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- ### Borders & Shadows

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- - **Frost Border** (`rgba(214, 235, 253, 0.19)`): The signature — icy blue-tinted borders at 19% opacity

- - **Frost Border Alt** (`rgba(217, 237, 254, 0.145)`): Slightly lighter variant for list items

- - **Ring Shadow** (`rgba(176, 199, 217, 0.145) 0px 0px 0px 1px`): Blue-tinted shadow-as-border

- - **Focus Ring** (`rgb(0, 0, 0) 0px 0px 0px 8px`): Heavy black focus ring

- - **Subtle Shadow** (`rgba(0, 0, 0, 0.1) 0px 1px 3px, rgba(0, 0, 0, 0.1) 0px 1px 2px -1px`): Minimal card elevation

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- ## 3. Typography Rules

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- ### Font Families

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- - **Display Serif**: `domaine` (Domaine Display by Klim Type Foundry) — hero headlines

- - **Display Sans**: `aBCFavorit` (ABC Favorit by Dinamo), fallbacks: `ui-sans-serif, system-ui` — section headings

- - **Body / UI**: `inter`, fallbacks: `ui-sans-serif, system-ui` — body text, buttons, navigation

- - **Monospace**: `commitMono`, fallbacks: `ui-monospace, SFMono-Regular, Menlo, Monaco, Consolas`

- - **Secondary**: `Helvetica` — fallback for specific UI contexts

- - **System**: `-apple-system, system-ui, Segoe UI, Roboto` — embedded content

-

- ### Hierarchy

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- | Role | Font | Size | Weight | Line Height | Letter Spacing | Notes |

- |------|------|------|--------|-------------|----------------|-------|

- | Display Hero | domaine | 96px (6.00rem) | 400 | 1.00 (tight) | -0.96px | `"ss01", "ss04", "ss11"` |

- | Display Hero Mobile | domaine | 76.8px (4.80rem) | 400 | 1.00 (tight) | -0.768px | Scaled for mobile |

- | Section Heading | aBCFavorit | 56px (3.50rem) | 400 | 1.20 (tight) | -2.8px | `"ss01", "ss04", "ss11"` |

- | Sub-heading | aBCFavorit | 20px (1.25rem) | 400 | 1.30 (tight) | normal | `"ss01", "ss04", "ss11"` |

- | Sub-heading Compact | aBCFavorit | 16px (1.00rem) | 400 | 1.50 | -0.8px | `"ss01", "ss04", "ss11"` |

- | Feature Title | inter | 24px (1.50rem) | 500 | 1.50 | normal | Section sub-headings |

- | Body Large | inter | 18px (1.13rem) | 400 | 1.50 | normal | Introductions |

- | Body | inter | 16px (1.00rem) | 400 | 1.50 | normal | Standard body text |

- | Body Semibold | inter | 16px (1.00rem) | 600 | 1.50 | normal | Emphasis, active states |

- | Nav Link | aBCFavorit | 14px (0.88rem) | 500 | 1.43 | 0.35px | `"ss01", "ss03", "ss04"` — positive tracking |

- | Button / Link | inter | 14px (0.88rem) | 500–600 | 1.43 | normal | Buttons, nav, CTAs |

- | Caption | inter | 14px (0.88rem) | 400 | 1.60 (relaxed) | normal | Descriptions |

- | Helvetica Caption | Helvetica | 14px (0.88rem) | 400–600 | 1.00–1.71 | normal | UI elements |

- | Small | inter | 12px (0.75rem) | 400–500 | 1.33 | normal | Tags, meta, fine print |

- | Small Uppercase | inter | 12px (0.75rem) | 500 | 1.33 | normal | `text-transform: uppercase` |

- | Small Capitalize | inter | 12px (0.75rem) | 500 | 1.33 | normal | `text-transform: capitalize` |

- | Code Body | commitMono | 16px (1.00rem) | 400 | 1.50 | normal | Code blocks |

- | Code Small | commitMono | 14px (0.88rem) | 400 | 1.43 | normal | Inline code |

- | Code Tiny | commitMono | 12px (0.75rem) | 400 | 1.33 | normal | Small code labels |

- | Heading (Helvetica) | Helvetica | 24px (1.50rem) | 400 | 1.40 | normal | Alternate heading context |

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- ### Principles

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- - **Three-font editorial hierarchy**: Domaine Display (serif, hero), ABC Favorit (geometric sans, sections), Inter (readable body). Each font has a strict role — they never cross lanes.

- - **Aggressive negative tracking on display**: Domaine at -0.96px, ABC Favorit at -2.8px. The display type feels compressed, urgent, and designed — like a magazine masthead.

- - **Positive tracking on nav**: ABC Favorit nav links use +0.35px letter-spacing — the only positive tracking in the system. This creates airy, spaced-out navigation text that contrasts with the compressed headings.

- - **OpenType as identity**: The `"ss01"`, `"ss03"`, `"ss04"`, `"ss11"` stylistic sets are enabled on all ABC Favorit and Domaine text, activating alternate glyphs that give Resend's typography its unique character.

- - **Commit Mono as design element**: The monospace font isn't hidden in code blocks — it's used prominently for code examples and technical content, treated as a first-class visual element.

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- ## 4. Component Stylings

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- ### Buttons

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- **Primary Transparent Pill**

- - Background: transparent

- - Text: `#f0f0f0`

- - Padding: 5px 12px

- - Radius: 9999px (full pill)

- - Border: `1px solid rgba(214, 235, 253, 0.19)` (frost border)

- - Hover: background `rgba(255, 255, 255, 0.28)` (white glass)

- - Use: Primary CTA on dark backgrounds

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- **White Solid Pill**

- - Background: `#ffffff`

- - Text: `#000000`

- - Padding: 5px 12px

- - Radius: 9999px

- - Use: High-contrast CTA ("Get started")

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- **Ghost Button**

- - Background: transparent

- - Text: `#f0f0f0`

- - Radius: 4px

- - No border

- - Hover: subtle background tint

- - Use: Secondary actions, tab items

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- ### Cards & Containers

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- - Background: transparent or very subtle dark tint

- - Border: `1px solid rgba(214, 235, 253, 0.19)` (frost border)

- - Radius: 16px (standard cards), 24px (large sections/panels)

- - Shadow: `rgba(176, 199, 217, 0.145) 0px 0px 0px 1px` (ring shadow)

- - Dark product screenshots and code demos as card content

- - No traditional box-shadow elevation

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- ### Inputs & Forms

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- - Text: `#f0f0f0` on dark, `#000000` on light

- - Radius: 4px

- - Focus: shadow-based ring

- - Minimal styling — inherits dark theme

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- ### Navigation

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- - Sticky dark header with frost border bottom: `1px solid rgba(214, 235, 253, 0.19)`

- - "Resend" wordmark left-aligned

- - ABC Favorit 14px weight 500 with +0.35px tracking for nav links

- - Pill CTAs right-aligned

- - Mobile: hamburger collapse

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- ### Image Treatment

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- - Product screenshots and code demos dominate content sections

- - Dark-themed screenshots on dark background — seamless integration

- - Rounded corners: 12px–16px on images

- - Full-width sections with subtle gradient overlays

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- ### Distinctive Components

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- **Tab Navigation**

- - Horizontal tabs with subtle selection indicator

- - Tab items: 8px radius

- - Active state with subtle background differentiation

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- **Code Preview Panels**

- - Dark code blocks using Commit Mono

- - Frost borders (`rgba(214, 235, 253, 0.19)`)

- - Syntax-highlighted with multi-color accent tokens (orange, blue, green, yellow)

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- **Multi-color Accent Badges**

- - Each product feature has its own accent color from the CSS variable scale

- - Badges use the accent color at low opacity (12–42%) for background, full opacity for text

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- ## 5. Layout Principles

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- ### Spacing System

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- - Base unit: 8px

- - Scale: 1px, 2px, 4px, 5px, 6px, 7px, 8px, 10px, 12px, 16px, 20px, 24px, 30px, 32px, 40px

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- ### Grid & Container

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- - Centered content with generous max-width

- - Full-width black sections with contained inner content

- - Single-column hero, expanding to feature grids below

- - Code preview panels as full-width or contained showcases

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- ### Whitespace Philosophy

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- - **Cinematic black space**: The black background IS the whitespace. Generous vertical spacing (80px–120px+) between sections creates a scroll-through-darkness experience where each section emerges like a scene.

- - **Tight content, vast surrounds**: Text blocks and cards are compact internally, but float in vast dark space — creating isolated "islands" of content.

- - **Typography-led rhythm**: The massive display fonts (96px) create their own vertical rhythm — each headline is a visual event that anchors the surrounding space.

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- ### Border Radius Scale

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- - Sharp (4px): Buttons (ghost), inputs, small interactive elements

- - Subtle (6px): Menu panels, navigation items

- - Standard (8px): Tabs, content blocks

- - Comfortable (10px): Accent elements

- - Card (12px): Clipboard buttons, medium containers

- - Large (16px): Feature cards, images, main buttons

- - Section (24px): Large panels, section containers

- - Pill (9999px): Primary CTAs, tags, badges

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- ## 6. Depth & Elevation

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- | Level | Treatment | Use |

- |-------|-----------|-----|

- | Flat (Level 0) | No shadow, transparent background | Default — most elements on dark void |

- | Ring (Level 1) | `rgba(176, 199, 217, 0.145) 0px 0px 0px 1px` | Shadow-as-border for cards, containers |

- | Frost Border (Level 1b) | `1px solid rgba(214, 235, 253, 0.19)` | Explicit borders — buttons, dividers, tabs |

- | Subtle (Level 2) | `rgba(0, 0, 0, 0.1) 0px 1px 3px, rgba(0, 0, 0, 0.1) 0px 1px 2px -1px` | Light card elevation |

- | Focus (Level 3) | `rgb(0, 0, 0) 0px 0px 0px 8px` | Heavy black focus ring — accessibility |

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- **Shadow Philosophy**: Resend barely uses shadows at all. On a pure black background, traditional shadows are invisible — you can't cast a shadow into the void. Instead, Resend creates depth through its signature frost borders (`rgba(214, 235, 253, 0.19)`) — thin, icy blue-tinted lines that catch light against the darkness. This creates a "glass panel floating in space" aesthetic where borders are the primary depth mechanism.

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- ### Decorative Depth

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- - Subtle warm gradient glows behind hero content (orange/amber tints)

- - Product screenshots create visual depth through their own internal UI

- - No gradient backgrounds — depth comes from border luminance and content contrast

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- ## 7. Do's and Don'ts

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- ### Do

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- - Use pure black (`#000000`) as the page background — the void is the canvas

- - Apply frost borders (`rgba(214, 235, 253, 0.19)`) for all structural lines — they're the blue-tinted signature

- - Use Domaine Display ONLY for hero headings (96px), ABC Favorit for section headings, Inter for everything else

- - Enable OpenType `"ss01"`, `"ss04"`, `"ss11"` on Domaine and ABC Favorit text

- - Apply pill radius (9999px) to primary CTAs and tags

- - Use the multi-color accent scale (orange/green/blue/yellow/red) with opacity variants for context-specific highlighting

- - Keep shadows at ring level (`0px 0px 0px 1px`) — on black, traditional shadows don't work

- - Use +0.35px letter-spacing on ABC Favorit nav links — the only positive tracking

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- ### Don't

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- - Don't lighten the background above `#000000` — the pure black void is non-negotiable

- - Don't use neutral gray borders — all borders must have the frost blue tint

- - Don't apply Domaine Display to body text — it's a display-only serif

- - Don't mix accent colors in the same component — each feature gets one accent color

- - Don't use box-shadow for elevation on the dark background — use frost borders instead

- - Don't skip the OpenType stylistic sets — they define the typographic character

- - Don't use negative letter-spacing on nav links — ABC Favorit nav uses positive +0.35px

- - Don't make buttons opaque on dark — transparency with frost border is the pattern

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- ## 8. Responsive Behavior

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- ### Breakpoints

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- | Name | Width | Key Changes |

- |------|-------|-------------|

- | Mobile Small | <480px | Single column, tight padding, 76.8px hero |

- | Mobile | 480–600px | Standard mobile, stacked layout |

- | Desktop | >600px | Full layout, 96px hero, expanded sections |

-

- *Note: Resend uses a minimal breakpoint system — only 480px and 600px detected. The design is desktop-first with a clean mobile collapse.*

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- ### Touch Targets

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- - Pill buttons: adequate padding (5px 12px minimum)

- - Tab items: 8px radius with comfortable hit areas

- - Navigation links spaced with 0.35px tracking for visual separation

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- ### Collapsing Strategy

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- - Hero: Domaine 96px → 76.8px on mobile

- - Navigation: horizontal → hamburger

- - Feature sections: side-by-side → stacked

- - Code panels: maintain width, horizontal scroll if needed

- - Spacing compresses proportionally

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- ### Image Behavior

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- - Product screenshots maintain aspect ratio

- - Dark screenshots blend seamlessly with dark background at all sizes

- - Rounded corners (12px–16px) maintained across breakpoints

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- ## 9. Agent Prompt Guide

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- ### Quick Color Reference

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- - Background: Void Black (`#000000`)

- - Primary text: Near White (`#f0f0f0`)

- - Secondary text: Silver (`#a1a4a5`)

- - Border: Frost Border (`rgba(214, 235, 253, 0.19)`)

- - Orange accent: `#ff801f`

- - Green accent: `#11ff99` (at 18% opacity)

- - Blue accent: `#3b9eff`

- - Focus ring: `rgb(0, 0, 0) 0px 0px 0px 8px`

- ### Example Component Prompts

- - "Create a hero section on pure black (#000000) background. Headline at 96px Domaine Display weight 400, line-height 1.00, letter-spacing -0.96px, near-white (#f0f0f0) text, OpenType 'ss01 ss04 ss11'. Subtitle at 20px ABC Favorit weight 400, line-height 1.30. Two pill buttons: white solid (#ffffff, 9999px radius) and transparent with frost border (rgba(214,235,253,0.19))."

- - "Design a navigation bar: dark background with frost border bottom (1px solid rgba(214,235,253,0.19)). Nav links at 14px ABC Favorit weight 500, letter-spacing +0.35px, OpenType 'ss01 ss03 ss04'. White pill CTA right-aligned."

- - "Build a feature card: transparent background, frost border (rgba(214,235,253,0.19)), 16px radius. Title at 56px ABC Favorit weight 400, letter-spacing -2.8px. Body at 16px Inter weight 400, #a1a4a5 text."

- - "Create a code block using Commit Mono 16px on dark background. Frost border container (24px radius). Syntax colors: orange (#ff801f), blue (#3b9eff), green (#11ff99), yellow (#ffc53d)."

- - "Design an accent badge: background #ff5900 at 22% opacity, text #ffa057, 9999px radius, 12px Inter weight 500."

- ### Iteration Guide

- 1. Start with pure black — everything floats in the void

- 2. Frost borders (`rgba(214, 235, 253, 0.19)`) are the universal structural element — not gray, not neutral

- 3. Three fonts, three roles: Domaine (hero), ABC Favorit (sections), Inter (body) — never cross

- 4. OpenType stylistic sets are mandatory on display fonts — they define the character

- 5. Multi-color accents at low opacity (12–42%) for backgrounds, full opacity for text

- 6. Pill shape (9999px) for CTAs and badges, standard radius (4px–16px) for containers

- 7. No shadows — use frost borders for depth against the void