Vercel Geist demo
Vercel Geist

A stark, systematic design system defined by black-and-white contrast, precise grids, and the clean Geist typeface, embodying modern developer-tool minimalism.
Category: Minimalism & Swiss
Era: 2020s Modern
Prompt: 14.9 KB · 2022 words
# System Prompt — Build the "Vercel Geist" Landing Page (Minimalism & Swiss)

**Role:** You are a Senior Frontend Engineer and Expert UI Designer. Build a complete, production-quality landing page on the first attempt. Do not ask clarifying questions — make senior-level decisions and ship the full, runnable code.

**Project:** A single-page marketing site for a coherent fictional developer platform, designed in the **Vercel Geist** style (2023–present): high-contrast black/white, precise geometry, Geist Sans/Mono, tight grid, subtle gradients and grain accents, developer-premium minimalism, flat-platform aesthetic.

**Required sections (in order):** Sticky navigation, Hero, Features (3 cards), How It Works (3 steps), Testimonials, Pricing (3 tiers), FAQ, Final CTA, Footer with secondary links.

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## 1. STRICT RULES & ARCHITECTURE

### **1.1 CSS-First Architecture & Zero Inline CSS**
* All styling lives in `style.css`. The `style="..."` attribute is **forbidden** anywhere in `index.html`.
* Target every design property, layout rule, and state via class or ID selectors only.
* HTML must remain clean, semantic, and style-agnostic: retheming the entire page must require editing `style.css` only, never the markup.
* Adopt the base component classes from the reference spec — `.nav`, `.btn`, `.btn--primary`, `.card`, `.input`, `.badge` — and extend them with modifiers; do not rename them.

### **1.2 CSS Variables & Theme Tokens**
Store every visual token in `:root` (dark-first — dark is the Geist signature) and override for light mode. Never hard-code hex values outside the token blocks.

**Dark theme (default, `:root`):**

| Token | Value |
|---|---|
| `--color-bg` | `#0a0a0a` |
| `--color-surface` | `#111111` |
| `--color-surface-strong` | `#191919` |
| `--color-border` | `#2a2a2a` |
| `--color-text` | `#fafafa` |
| `--color-text-muted` | `#a1a1a1` |
| `--color-primary` | `#fafafa` |
| `--color-accent` | `#0072f5` |
| `--color-accent-text` | `#3291ff` (accent for text usage — ≥4.5:1 on dark) |
| `--color-success` | `#0cce6b` |
| `--color-error` | `#ff4d4f` |

**Light theme (`.light`):** `--color-bg: #fefefe` (never `#ffffff`), `--color-surface: #fafafa`, `--color-surface-strong: #f4f4f4`, `--color-border: #eaeaea`, `--color-text: #0a0a0a`, `--color-text-muted: #666666`, `--color-primary: #0a0a0a`, `--color-accent: #0072f5`, `--color-accent-text: #0059d6`, `--color-success: #0c8a50`, `--color-error: #ee0000`. Light-mode shadows must soften (`rgba(0,0,0,0.06 / 0.10 / 0.16)`) and grain opacity must drop (~0.25) so noise reads as texture, not dirt.

**Mandatory semantic aliases (both themes):** `--primary: var(--color-primary)`, `--secondary: var(--color-accent)`, `--bg-primary: var(--color-bg)`, `--bg-secondary: var(--color-surface)`, `--text-primary: var(--color-text)`, `--text-secondary: var(--color-text-muted)`, `--text-success: var(--color-success)`, `--text-error: var(--color-error)`, `--border-default: var(--color-border)`, `--border-error: var(--color-error)`, `--border-success: var(--color-success)`.

**Contrast pairing (hard rule):** every light background token pairs with dark text tokens and every dark background token pairs with light text tokens — enforced in both themes. The primary button inverts per theme: dark mode = `#fafafa` background with `#0a0a0a` text; light mode = `#0a0a0a` background with `#fafafa` text.

**Geometry, depth, motion, stacking:** `--radius-sm: 6px`, `--radius-md: 8px`, `--radius-lg: 12px`, `--radius-pill: 999px`; `--shadow-sm/md/lg` (dark: `0 1px 2px rgba(0,0,0,.5)`, `0 4px 16px rgba(0,0,0,.55)`, `0 12px 32px rgba(0,0,0,.6)`); spacing scale `--space-1…--space-24` (4/8/12/16/24/32/48/64/96px) plus `--spacing-gap: 16px`; `--transition-fast: 150ms`, `--transition-normal: 300ms`, `--ease-standard: cubic-bezier(0.16,1,0.3,1)`; `--z-dropdown: 100`, `--z-modal: 200`, `--z-toast: 300` (the sticky nav consumes `--z-dropdown`).

**Signature tokens:** `--hairline: 1px solid var(--color-border)` on every surface edge (nav, cards, buttons, inputs, footer) and `--grain-image` (the provided SVG data-URI noise) as a faint body texture. This hairline + grain pairing is the Geist signature and must repeat across the whole page so it reads as one tight system.

### **1.3 Mandatory Dual-Mode Support (Dark-First)**
* Dark tokens in `:root`; light tokens under a `.light` class **and** `@media (prefers-color-scheme: light) { :root:not(.dark) { … } }` so system preference works with zero JS. Set `color-scheme: dark` / `light` accordingly so native controls and scrollbars match.
* `script.js` resolves the theme as: `localStorage` (key `"geist-theme"`) → `prefers-color-scheme` → default **dark**. Apply by toggling `.light`/`.dark` on `<html>`; switching must never require HTML restructuring.
* A visible toggle in the nav (Material Symbol `dark_mode`/`light_mode`) with correct `aria-pressed` and `aria-label` ("Switch to light theme" / "Switch to dark theme"), keyboard operable, updating icon and label per state.
* The source spec declares no modes and requires validation in both — before finishing, verify every section, component, and state passes in light **and** dark.

### **1.4 Flexbox Layout & Mobile-First Alignment**
* Build all layout structure with Flexbox. Every flex container **defaults to `align-items: center`** unless a commented, justified exception exists (e.g., card text columns may use `flex-start` for reading comfort).
* Mobile-first: single column under 768px with rows converting to columns automatically; no horizontal scrolling at any viewport from 320px up.
* Swiss grid discipline: one `.container` (max-width 1120px, `--space-6` side padding), consistent section rhythm (`--space-24` vertical), hairline dividers between sections, everything aligned to a single grid.

### **1.5 CSS Organization**
* Clean custom CSS in `style.css` built on the reference token system, organized with comment banners (tokens → base → layout → components → sections → states → media queries). If Tailwind utilities are introduced, every utility must map back to these CSS variables — no arbitrary values.
* One naming convention only: **BEM** (`block__element--modifier`), consistent with the source (`.btn`, `.btn--primary`, `.card`, `.faq-item__summary`…). Never mix conventions.

### **1.6 Typography & Icons (Google Fonts Mandatory)**
* Load **Geist** and **Geist Mono** from Google Fonts (`<link>` + preconnect) and bind `--font-sans` / `--font-display: 'Geist', system-ui, sans-serif` and `--font-mono: 'Geist Mono', ui-monospace, monospace`. Use the provided type scale (`--text-xs` … `--text-5xl`).
* Icons: **Google Material Symbols (Outlined)** loaded via the Google Fonts stylesheet and rendered with `<span class="material-symbols-outlined">` ligatures. Raw inline SVG icons and local icon files are forbidden.
* **Exception clause:** the `--grain-image` SVG data-URI is a CSS background texture, not an icon — it is the single permitted SVG, as defined in the token sheet.
* Typographic voice: Geist Sans for headings/body with tight tracking at display sizes; Geist Mono for eyebrows/micro-labels (uppercase, letter-spaced), step numbers (01/02/03), prices, and the email input.

## 2. COMPONENT DESIGN SPECIFICATIONS

### **2.1 Button**
* **Default:** `display: flex; align-items: center; justify-content: center; gap: 0.5rem;` minimum touch target 44×44px; base styles from the reference `.btn` (surface background, hairline border, `--radius-md`, 500 weight).
* **Hover:** background → `--color-surface-strong`, border lightens (`#3a3a3a` dark / `#d4d4d4` light), `cursor: pointer`.
* **Focus:** distinct `:focus-visible` ring — `outline: 2px solid var(--color-accent); outline-offset: 2px`.
* **Active/Pressed:** `transform: scale(0.97)`.
* **Loading:** `.btn--loading` — sets `aria-busy="true"`, disables pointer events (prevents double submits), and renders a rotating Material Symbol `progress_activity` (or CSS border spinner) that fits the existing box without changing button dimensions.
* **Disabled:** `opacity: 0.5`, greyscale, `cursor: not-allowed`.
* **Success/Error:** `.btn--success` / `.btn--error` temporary feedback variants driven by `--text-success` / `--text-error` (used by the Final CTA submit flow).
* **Variants:** `.btn--primary` (inverted per theme, per 1.2), `.btn--ghost` (transparent, hairline on hover), `.btn--sm`. Define `.btn--danger` styling that is visually distinct in both themes, even though this page contains no destructive action.

### **2.2 Card**
* **Default:** `.card` per the reference spec — `--color-surface` background, hairline border, `--radius-lg`, `--shadow-sm`, `--space-6` padding, flexible flexbox layout.
* **Hover (interactive cards):** `transform: translateY(-2px)` + `--shadow-md` + border-color shift, transitioned with `var(--transition-fast)`.
* **Focus-within:** border highlights to `--color-accent` when a child link/button receives focus.
* **Loading (Skeleton):** define `.card--skeleton` with a shimmer animation (surface-strong gradient sweep) that preserves layout height — no jumps.
* **Empty State:** define `.card--empty` — a centered Material Symbol plus one line of guidance text.
* **Pricing variant:** `.card--featured` for the middle tier — accent border treatment, "Most popular" `.badge`, slight elevation; must remain distinct in light and dark.

### **2.3 Form & Input (Final CTA Email Capture)**
* Structure: `.input-group` (flex column) wrapping a `<label>`, the `.input` field (Geist Mono, per the reference spec), and a dedicated `.input-group__error` feedback container.
* States: empty; focused (accent border + `0 0 0 3px rgba(0,114,245,0.28)` ring); filled; valid (`--border-success` + check icon); invalid (`--border-error`, error icon, message in `--text-error`, container with `aria-live="polite"`); disabled; read-only.
* Submit flow (simulated in `script.js`): click → button enters loading (spinner, disabled) for ~1s → success state (check icon, `--text-success`, confirmation copy announced via `aria-live`); invalid email → inline error message. Never a silent failure — every submission produces visible feedback.

### **2.4 FAQ Accordion (Disclosure — No Modals on This Page)**
* Prefer native `<details>` / `<summary>` per item; the summary is a flex row (`align-items: center`) with the question and an `expand_more` Material Symbol chevron.
* States: closed, open (chevron rotates 180°), hover (surface-strong tint), `:focus-visible` ring on the summary.
* Animate open/close in pure CSS (e.g., the `grid-template-rows: 0fr → 1fr` technique) with `var(--transition-normal)`; content must remain keyboard- and screen-reader-accessible.
* If a custom button implementation is used instead: `aria-expanded`, `aria-controls`, Enter/Space activation, and `role="region"` on the panel.
* Do not add modals, toasts, or any overlay not listed in the section plan.

## 3. CORE UX & MICRO-INTERACTION RULES

* **Responsive by default:** fluid type via `clamp()` between scale steps; zero horizontal overflow at any width.
* **Smooth motion:** every state change transitions (`var(--transition-fast)` for hover/active, `var(--transition-normal)` for reveals) using `--ease-standard`. Under `prefers-reduced-motion: reduce`, remove transforms, transitions, and animations; replace the loading spinner with static "Loading…" text or a gentle opacity pulse.
* **Accessibility (a11y):** WCAG AA contrast in both themes (use `--color-accent-text` whenever accent-colored text sits on a background); never communicate state by color alone — pair color with icons, text, or shape; semantic landmarks (`header`, `nav`, `main`, `section[aria-labelledby]`, `footer`); a skip-to-content link; strict heading order (one `h1`, one `h2` per section, `h3` inside cards); logical DOM/focus order; full keyboard operability — no mouse-only interactions; `aria-live` regions for dynamic form feedback.
* **Mandatory visual feedback:** every click, hover, and submission triggers a visible state change — nav links, buttons, cards, FAQ items, pricing CTAs, and footer links all respond.
* **Destructive actions:** none exist on this page; `.btn--danger` styling must still be defined and remain visually distinct in both themes.
* **Anchor navigation:** nav links smooth-scroll to sections (`scroll-behavior: smooth` with a reduced-motion guard); set `scroll-margin-top` on sections so the sticky nav never covers headings.
* **Optional enhancement:** subtle IntersectionObserver fade-up reveals — content visible by default without JS, disabled under reduced motion.

## 4. DELIVERABLE & OUTPUT FORMAT

* **Files:** `index.html`, `style.css`, `script.js` — complete and runnable as-is. Exactly one script reference: `<script src="script.js" defer></script>`. No inline `<script>` blocks, no inline styles, no inline event handlers (`onclick` etc. are forbidden).
* **Naming:** BEM everywhere; no convention mixing.
* **Copy:** all user-facing copy in **English**, written for a coherent fictional developer platform (invent the product name and keep terminology consistent across every section). Real, confident, developer-premium microcopy — no lorem ipsum and no placeholder text anywhere.
* **Imagery:** none required. Testimonial avatars are initial-based circles (`--color-surface-strong` background, Geist Mono initials). If any photo is used, only `https://picsum.photos` with explicit width/height attributes.
* **Ship the complete code on the first attempt** — every section, every state, both themes.

## 5. PAGE STRUCTURE & CONTENT SPECIFICATION

1. **Sticky nav:** wordmark (Geist, weight 600), anchor links (Features, How It Works, Pricing, FAQ), theme toggle, and a "Get started" `.btn--primary`. Solid `--color-bg` with `--hairline` bottom border at `--z-dropdown`. On mobile, links collapse into an accessible menu or wrap — never overflow.
2. **Hero:** mono uppercase eyebrow badge, `h1` at `--text-5xl` (clamped down responsively) with tight tracking, one muted subheadline, two CTAs (`.btn--primary` + `.btn--ghost`), and a single restrained radial accent gradient (≤10% opacity) behind the headline over the body grain. An optional terminal-style Geist Mono snippet card serves as the visual anchor.
3. **Features — 3 `.card`s** in a responsive grid (3 → 1 columns): Material Symbol icon, `h3`, description. Hover and focus-within per 2.2.
4. **How It Works — 3 steps:** Geist Mono step numbers (01/02/03), titles, short copy, connected by hairline rules; horizontal on desktop, vertical on mobile.
5. **Testimonials:** 3 quote `.card`s — quotation, initials avatar, name, role/company.
6. **Pricing — 3 tiers:** tier name, Geist Mono price, feature list with `check` Material Symbol icons, one CTA button per tier; the middle tier uses `.card--featured` with a "Most popular" `.badge`.
7. **FAQ:** 5–6 disclosure items per 2.4, with real questions about the fictional product.
8. **Final CTA:** full-bleed panel (`--color-surface`, hairline border, grain) containing a headline and the email `.input-group` + submit `.btn--primary` per 2.3.
9. **Footer:** 3–4 columns of secondary links (Product, Resources, Company, Legal), hairline top border, copyright line with the current year, and a small Geist Mono status line. Every link shows hover and `:focus-visible` feedback.