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+# Design System: Linear
+
+## 1. Visual Theme & Atmosphere
+
+Linear's website is a masterclass in dark-mode-first product design — a near-black canvas (`#08090a`) where content emerges from darkness like starlight. The overall impression is one of extreme precision engineering: every element exists in a carefully calibrated hierarchy of luminance, from barely-visible borders (`rgba(255,255,255,0.05)`) to soft, luminous text (`#f7f8f8`). This is not a dark theme applied to a light design — it is darkness as the native medium, where information density is managed through subtle gradations of white opacity rather than color variation.
+
+The typography system is built entirely on Inter Variable with OpenType features `"cv01"` and `"ss03"` enabled globally, giving the typeface a cleaner, more geometric character. Inter is used at a remarkable range of weights — from 300 (light body) through 510 (medium, Linear's signature weight) to 590 (semibold emphasis). The 510 weight is particularly distinctive: it sits between regular and medium, creating a subtle emphasis that doesn't shout. At display sizes (72px, 64px, 48px), Inter uses aggressive negative letter-spacing (-1.584px to -1.056px), creating compressed, authoritative headlines that feel engineered rather than designed. Berkeley Mono serves as the monospace companion for code and technical labels, with fallbacks to ui-monospace, SF Mono, and Menlo.
+
+The color system is almost entirely achromatic — dark backgrounds with white/gray text — punctuated by a single brand accent: Linear's signature indigo-violet (`#5e6ad2` for backgrounds, `#7170ff` for interactive accents). This accent color is used sparingly and intentionally, appearing only on CTAs, active states, and brand elements. The border system uses ultra-thin, semi-transparent white borders (`rgba(255,255,255,0.05)` to `rgba(255,255,255,0.08)`) that create structure without visual noise, like wireframes drawn in moonlight.
+
+**Key Characteristics:**
+- Dark-mode-native: `#08090a` marketing background, `#0f1011` panel background, `#191a1b` elevated surfaces
+- Inter Variable with `"cv01", "ss03"` globally — geometric alternates for a cleaner aesthetic
+- Signature weight 510 (between regular and medium) for most UI text
+- Aggressive negative letter-spacing at display sizes (-1.584px at 72px, -1.056px at 48px)
+- Brand indigo-violet: `#5e6ad2` (bg) / `#7170ff` (accent) / `#828fff` (hover) — the only chromatic color in the system
+- Semi-transparent white borders throughout: `rgba(255,255,255,0.05)` to `rgba(255,255,255,0.08)`
+- Button backgrounds at near-zero opacity: `rgba(255,255,255,0.02)` to `rgba(255,255,255,0.05)`
+- Multi-layered shadows with inset variants for depth on dark surfaces
+- Radix UI primitives as the component foundation (6 detected primitives)
+- Success green (`#27a644`, `#10b981`) used only for status indicators
+
+## 2. Color Palette & Roles
+
+### Background Surfaces
+- **Marketing Black** (`#010102` / `#08090a`): The deepest background — the canvas for hero sections and marketing pages. Near-pure black with an imperceptible blue-cool undertone.
+- **Panel Dark** (`#0f1011`): Sidebar and panel backgrounds. One step up from the marketing black.
+- **Level 3 Surface** (`#191a1b`): Elevated surface areas, card backgrounds, dropdowns.
+- **Secondary Surface** (`#28282c`): The lightest dark surface — used for hover states and slightly elevated components.
+
+### Text & Content
+- **Primary Text** (`#f7f8f8`): Near-white with a barely-warm cast. The default text color — not pure white, preventing eye strain on dark backgrounds.
+- **Secondary Text** (`#d0d6e0`): Cool silver-gray for body text, descriptions, and secondary content.
+- **Tertiary Text** (`#8a8f98`): Muted gray for placeholders, metadata, and de-emphasized content.
+- **Quaternary Text** (`#62666d`): The most subdued text — timestamps, disabled states, subtle labels.
+
+### Brand & Accent
+- **Brand Indigo** (`#5e6ad2`): Primary brand color — used for CTA button backgrounds, brand marks, and key interactive surfaces.
+- **Accent Violet** (`#7170ff`): Brighter variant for interactive elements — links, active states, selected items.
+- **Accent Hover** (`#828fff`): Lighter, more saturated variant for hover states on accent elements.
+- **Security Lavender** (`#7a7fad`): Muted indigo used specifically for security-related UI elements.
+
+### Status Colors
+- **Green** (`#27a644`): Primary success/active status. Used for "in progress" indicators.
+- **Emerald** (`#10b981`): Secondary success — pill badges, completion states.
+
+### Border & Divider
+- **Border Primary** (`#23252a`): Solid dark border for prominent separations.
+- **Border Secondary** (`#34343a`): Slightly lighter solid border.
+- **Border Tertiary** (`#3e3e44`): Lightest solid border variant.
+- **Border Subtle** (`rgba(255,255,255,0.05)`): Ultra-subtle semi-transparent border — the default.
+- **Border Standard** (`rgba(255,255,255,0.08)`): Standard semi-transparent border for cards, inputs, code blocks.
+- **Line Tint** (`#141516`): Nearly invisible line for the subtlest divisions.
+- **Line Tertiary** (`#18191a`): Slightly more visible divider line.
+
+### Light Mode Neutrals (for light theme contexts)
+- **Light Background** (`#f7f8f8`): Page background in light mode.
+- **Light Surface** (`#f3f4f5` / `#f5f6f7`): Subtle surface tinting.
+- **Light Border** (`#d0d6e0`): Visible border in light contexts.
+- **Light Border Alt** (`#e6e6e6`): Alternative lighter border.
+- **Pure White** (`#ffffff`): Card surfaces, highlights.
+
+### Overlay
+- **Overlay Primary** (`rgba(0,0,0,0.85)`): Modal/dialog backdrop — extremely dark for focus isolation.
+
+## 3. Typography Rules
+
+### Font Family
+- **Primary**: `Inter Variable`, with fallbacks: `SF Pro Display, -apple-system, system-ui, Segoe UI, Roboto, Oxygen, Ubuntu, Cantarell, Open Sans, Helvetica Neue`
+- **Monospace**: `Berkeley Mono`, with fallbacks: `ui-monospace, SF Mono, Menlo`
+- **OpenType Features**: `"cv01", "ss03"` enabled globally — cv01 provides an alternate lowercase 'a' (single-story), ss03 adjusts specific letterforms for a cleaner geometric appearance.
+
+### Hierarchy
+
+| Role | Font | Size | Weight | Line Height | Letter Spacing | Notes |
+|------|------|------|--------|-------------|----------------|-------|
+| Display XL | Inter Variable | 72px (4.50rem) | 510 | 1.00 (tight) | -1.584px | Hero headlines, maximum impact |
+| Display Large | Inter Variable | 64px (4.00rem) | 510 | 1.00 (tight) | -1.408px | Secondary hero text |
+| Display | Inter Variable | 48px (3.00rem) | 510 | 1.00 (tight) | -1.056px | Section headlines |
+| Heading 1 | Inter Variable | 32px (2.00rem) | 400 | 1.13 (tight) | -0.704px | Major section titles |
+| Heading 2 | Inter Variable | 24px (1.50rem) | 400 | 1.33 | -0.288px | Sub-section headings |
+| Heading 3 | Inter Variable | 20px (1.25rem) | 590 | 1.33 | -0.24px | Feature titles, card headers |
+| Body Large | Inter Variable | 18px (1.13rem) | 400 | 1.60 (relaxed) | -0.165px | Introduction text, feature descriptions |
+| Body Emphasis | Inter Variable | 17px (1.06rem) | 590 | 1.60 (relaxed) | normal | Emphasized body, sub-headings in content |
+| Body | Inter Variable | 16px (1.00rem) | 400 | 1.50 | normal | Standard reading text |
+| Body Medium | Inter Variable | 16px (1.00rem) | 510 | 1.50 | normal | Navigation, labels |
+| Body Semibold | Inter Variable | 16px (1.00rem) | 590 | 1.50 | normal | Strong emphasis |
+| Small | Inter Variable | 15px (0.94rem) | 400 | 1.60 (relaxed) | -0.165px | Secondary body text |
+| Small Medium | Inter Variable | 15px (0.94rem) | 510 | 1.60 (relaxed) | -0.165px | Emphasized small text |
+| Small Semibold | Inter Variable | 15px (0.94rem) | 590 | 1.60 (relaxed) | -0.165px | Strong small text |
+| Small Light | Inter Variable | 15px (0.94rem) | 300 | 1.47 | -0.165px | De-emphasized body |
+| Caption Large | Inter Variable | 14px (0.88rem) | 510–590 | 1.50 | -0.182px | Sub-labels, category headers |
+| Caption | Inter Variable | 13px (0.81rem) | 400–510 | 1.50 | -0.13px | Metadata, timestamps |
+| Label | Inter Variable | 12px (0.75rem) | 400–590 | 1.40 | normal | Button text, small labels |
+| Micro | Inter Variable | 11px (0.69rem) | 510 | 1.40 | normal | Tiny labels |
+| Tiny | Inter Variable | 10px (0.63rem) | 400–510 | 1.50 | -0.15px | Overline text, sometimes uppercase |
+| Link Large | Inter Variable | 16px (1.00rem) | 400 | 1.50 | normal | Standard links |
+| Link Medium | Inter Variable | 15px (0.94rem) | 510 | 2.67 | normal | Spaced navigation links |
+| Link Small | Inter Variable | 14px (0.88rem) | 510 | 1.50 | normal | Compact links |
+| Link Caption | Inter Variable | 13px (0.81rem) | 400–510 | 1.50 | -0.13px | Footer, metadata links |
+| Mono Body | Berkeley Mono | 14px (0.88rem) | 400 | 1.50 | normal | Code blocks |
+| Mono Caption | Berkeley Mono | 13px (0.81rem) | 400 | 1.50 | normal | Code labels |
+| Mono Label | Berkeley Mono | 12px (0.75rem) | 400 | 1.40 | normal | Code metadata, sometimes uppercase |
+
+### Principles
+- **510 is the signature weight**: Linear uses Inter Variable's 510 weight (between regular 400 and medium 500) as its default emphasis weight. This creates a subtly bolded feel without the heaviness of traditional medium or semibold.
+- **Compression at scale**: Display sizes use progressively tighter letter-spacing — -1.584px at 72px, -1.408px at 64px, -1.056px at 48px, -0.704px at 32px. Below 24px, spacing relaxes toward normal.
+- **OpenType as identity**: `"cv01", "ss03"` aren't decorative — they transform Inter into Linear's distinctive typeface, giving it a more geometric, purposeful character.
+- **Three-tier weight system**: 400 (reading), 510 (emphasis/UI), 590 (strong emphasis). The 300 weight appears only in deliberately de-emphasized contexts.
+
+## 4. Component Stylings
+
+### Buttons
+
+**Ghost Button (Default)**
+- Background: `rgba(255,255,255,0.02)`
+- Text: `#e2e4e7` (near-white)
+- Padding: comfortable
+- Radius: 6px
+- Border: `1px solid rgb(36, 40, 44)`
+- Outline: none
+- Focus shadow: `rgba(0,0,0,0.1) 0px 4px 12px`
+- Use: Standard actions, secondary CTAs
+
+**Subtle Button**
+- Background: `rgba(255,255,255,0.04)`
+- Text: `#d0d6e0` (silver-gray)
+- Padding: 0px 6px
+- Radius: 6px
+- Use: Toolbar actions, contextual buttons
+
+**Primary Brand Button (Inferred)**
+- Background: `#5e6ad2` (brand indigo)
+- Text: `#ffffff`
+- Padding: 8px 16px
+- Radius: 6px
+- Hover: `#828fff` shift
+- Use: Primary CTAs ("Start building", "Sign up")
+
+**Icon Button (Circle)**
+- Background: `rgba(255,255,255,0.03)` or `rgba(255,255,255,0.05)`
+- Text: `#f7f8f8` or `#ffffff`
+- Radius: 50%
+- Border: `1px solid rgba(255,255,255,0.08)`
+- Use: Close, menu toggle, icon-only actions
+
+**Pill Button**
+- Background: transparent
+- Text: `#d0d6e0`
+- Padding: 0px 10px 0px 5px
+- Radius: 9999px
+- Border: `1px solid rgb(35, 37, 42)`
+- Use: Filter chips, tags, status indicators
+
+**Small Toolbar Button**
+- Background: `rgba(255,255,255,0.05)`
+- Text: `#62666d` (muted)
+- Radius: 2px
+- Border: `1px solid rgba(255,255,255,0.05)`
+- Shadow: `rgba(0,0,0,0.03) 0px 1.2px 0px 0px`
+- Font: 12px weight 510
+- Use: Toolbar actions, quick-access controls
+
+### Cards & Containers
+- Background: `rgba(255,255,255,0.02)` to `rgba(255,255,255,0.05)` (never solid — always translucent)
+- Border: `1px solid rgba(255,255,255,0.08)` (standard) or `1px solid rgba(255,255,255,0.05)` (subtle)
+- Radius: 8px (standard), 12px (featured), 22px (large panels)
+- Shadow: `rgba(0,0,0,0.2) 0px 0px 0px 1px` or layered multi-shadow stacks
+- Hover: subtle background opacity increase
+
+### Inputs & Forms
+
+**Text Area**
+- Background: `rgba(255,255,255,0.02)`
+- Text: `#d0d6e0`
+- Border: `1px solid rgba(255,255,255,0.08)`
+- Padding: 12px 14px
+- Radius: 6px
+
+**Search Input**
+- Background: transparent
+- Text: `#f7f8f8`
+- Padding: 1px 32px (icon-aware)
+
+**Button-style Input**
+- Text: `#8a8f98`
+- Padding: 1px 6px
+- Radius: 5px
+- Focus shadow: multi-layer stack
+
+### Badges & Pills
+
+**Success Pill**
+- Background: `#10b981`
+- Text: `#f7f8f8`
+- Radius: 50% (circular)
+- Font: 10px weight 510
+- Use: Status dots, completion indicators
+
+**Neutral Pill**
+- Background: transparent
+- Text: `#d0d6e0`
+- Padding: 0px 10px 0px 5px
+- Radius: 9999px
+- Border: `1px solid rgb(35, 37, 42)`
+- Font: 12px weight 510
+- Use: Tags, filter chips, category labels
+
+**Subtle Badge**
+- Background: `rgba(255,255,255,0.05)`
+- Text: `#f7f8f8`
+- Padding: 0px 8px 0px 2px
+- Radius: 2px
+- Border: `1px solid rgba(255,255,255,0.05)`
+- Font: 10px weight 510
+- Use: Inline labels, version tags
+
+### Navigation
+- Dark sticky header on near-black background
+- Linear logomark left-aligned (SVG icon)
+- Links: Inter Variable 13–14px weight 510, `#d0d6e0` text
+- Active/hover: text lightens to `#f7f8f8`
+- CTA: Brand indigo button or ghost button
+- Mobile: hamburger collapse
+- Search: command palette trigger (`/` or `Cmd+K`)
+
+### Image Treatment
+- Product screenshots on dark backgrounds with subtle border (`rgba(255,255,255,0.08)`)
+- Top-rounded images: `12px 12px 0px 0px` radius
+- Dashboard/issue previews dominate feature sections
+- Subtle shadow beneath screenshots: `rgba(0,0,0,0.4) 0px 2px 4px`
+
+## 5. Layout Principles
+
+### Spacing System
+- Base unit: 8px
+- Scale: 1px, 4px, 7px, 8px, 11px, 12px, 16px, 19px, 20px, 22px, 24px, 28px, 32px, 35px
+- The 7px and 11px values suggest micro-adjustments for optical alignment
+- Primary rhythm: 8px, 16px, 24px, 32px (standard 8px grid)
+
+### Grid & Container
+- Max content width: approximately 1200px
+- Hero: centered single-column with generous vertical padding
+- Feature sections: 2–3 column grids for feature cards
+- Full-width dark sections with internal max-width constraints
+- Changelog: single-column timeline layout
+
+### Whitespace Philosophy
+- **Darkness as space**: On Linear's dark canvas, empty space isn't white — it's absence. The near-black background IS the whitespace, and content emerges from it.
+- **Compressed headlines, expanded surroundings**: Display text at 72px with -1.584px tracking is dense and compressed, but sits within vast dark padding. The contrast between typographic density and spatial generosity creates tension.
+- **Section isolation**: Each feature section is separated by generous vertical padding (80px+) with no visible dividers — the dark background provides natural separation.
+
+### Border Radius Scale
+- Micro (2px): Inline badges, toolbar buttons, subtle tags
+- Standard (4px): Small containers, list items
+- Comfortable (6px): Buttons, inputs, functional elements
+- Card (8px): Cards, dropdowns, popovers
+- Panel (12px): Panels, featured cards, section containers
+- Large (22px): Large panel elements
+- Full Pill (9999px): Chips, filter pills, status tags
+- Circle (50%): Icon buttons, avatars, status dots
+
+## 6. Depth & Elevation
+
+| Level | Treatment | Use |
+|-------|-----------|-----|
+| Flat (Level 0) | No shadow, `#010102` bg | Page background, deepest canvas |
+| Subtle (Level 1) | `rgba(0,0,0,0.03) 0px 1.2px 0px` | Toolbar buttons, micro-elevation |
+| Surface (Level 2) | `rgba(255,255,255,0.05)` bg + `1px solid rgba(255,255,255,0.08)` border | Cards, input fields, containers |
+| Inset (Level 2b) | `rgba(0,0,0,0.2) 0px 0px 12px 0px inset` | Recessed panels, inner shadows |
+| Ring (Level 3) | `rgba(0,0,0,0.2) 0px 0px 0px 1px` | Border-as-shadow technique |
+| Elevated (Level 4) | `rgba(0,0,0,0.4) 0px 2px 4px` | Floating elements, dropdowns |
+| Dialog (Level 5) | Multi-layer stack: `rgba(0,0,0,0) 0px 8px 2px, rgba(0,0,0,0.01) 0px 5px 2px, rgba(0,0,0,0.04) 0px 3px 2px, rgba(0,0,0,0.07) 0px 1px 1px, rgba(0,0,0,0.08) 0px 0px 1px` | Popovers, command palette, modals |
+| Focus | `rgba(0,0,0,0.1) 0px 4px 12px` + additional layers | Keyboard focus on interactive elements |
+
+**Shadow Philosophy**: On dark surfaces, traditional shadows (dark on dark) are nearly invisible. Linear solves this by using semi-transparent white borders as the primary depth indicator. Elevation isn't communicated through shadow darkness but through background luminance steps — each level slightly increases the white opacity of the surface background (`0.02` → `0.04` → `0.05`), creating a subtle stacking effect. The inset shadow technique (`rgba(0,0,0,0.2) 0px 0px 12px 0px inset`) creates a unique "sunken" effect for recessed panels, adding dimensional depth that traditional dark themes lack.
+
+## 7. Do's and Don'ts
+
+### Do
+- Use Inter Variable with `"cv01", "ss03"` on ALL text — these features are fundamental to Linear's typeface identity
+- Use weight 510 as your default emphasis weight — it's Linear's signature between-weight
+- Apply aggressive negative letter-spacing at display sizes (-1.584px at 72px, -1.056px at 48px)
+- Build on near-black backgrounds: `#08090a` for marketing, `#0f1011` for panels, `#191a1b` for elevated surfaces
+- Use semi-transparent white borders (`rgba(255,255,255,0.05)` to `rgba(255,255,255,0.08)`) instead of solid dark borders
+- Keep button backgrounds nearly transparent: `rgba(255,255,255,0.02)` to `rgba(255,255,255,0.05)`
+- Reserve brand indigo (`#5e6ad2` / `#7170ff`) for primary CTAs and interactive accents only
+- Use `#f7f8f8` for primary text — not pure `#ffffff`, which would be too harsh
+- Apply the luminance stacking model: deeper = darker bg, elevated = slightly lighter bg
+
+### Don't
+- Don't use pure white (`#ffffff`) as primary text — `#f7f8f8` prevents eye strain
+- Don't use solid colored backgrounds for buttons — transparency is the system (rgba white at 0.02–0.05)
+- Don't apply the brand indigo decoratively — it's reserved for interactive/CTA elements only
+- Don't use positive letter-spacing on display text — Inter at large sizes always runs negative
+- Don't use visible/opaque borders on dark backgrounds — borders should be whisper-thin semi-transparent white
+- Don't skip the OpenType features (`"cv01", "ss03"`) — without them, it's generic Inter, not Linear's Inter
+- Don't use weight 700 (bold) — Linear's maximum weight is 590, with 510 as the workhorse
+- Don't introduce warm colors into the UI chrome — the palette is cool gray with blue-violet accent only
+- Don't use drop shadows for elevation on dark surfaces — use background luminance stepping instead
+
+## 8. Responsive Behavior
+
+### Breakpoints
+| Name | Width | Key Changes |
+|------|-------|-------------|
+| Mobile Small | <600px | Single column, compact padding |
+| Mobile | 600–640px | Standard mobile layout |
+| Tablet | 640–768px | Two-column grids begin |
+| Desktop Small | 768–1024px | Full card grids, expanded padding |
+| Desktop | 1024–1280px | Standard desktop, full navigation |
+| Large Desktop | >1280px | Full layout, generous margins |
+
+### Touch Targets
+- Buttons use comfortable padding with 6px radius minimum
+- Navigation links at 13–14px with adequate spacing
+- Pill tags have 10px horizontal padding for touch accessibility
+- Icon buttons at 50% radius ensure circular, easy-to-tap targets
+- Search trigger is prominently placed with generous hit area
+
+### Collapsing Strategy
+- Hero: 72px → 48px → 32px display text, tracking adjusts proportionally
+- Navigation: horizontal links + CTAs → hamburger menu at 768px
+- Feature cards: 3-column → 2-column → single column stacked
+- Product screenshots: maintain aspect ratio, may reduce padding
+- Changelog: timeline maintains single-column through all sizes
+- Footer: multi-column → stacked single column
+- Section spacing: 80px+ → 48px on mobile
+
+### Image Behavior
+- Dashboard screenshots maintain border treatment at all sizes
+- Hero visuals simplify on mobile (fewer floating UI elements)
+- Product screenshots use responsive sizing with consistent radius
+- Dark background ensures screenshots blend naturally at any viewport
+
+## 9. Agent Prompt Guide
+
+### Quick Color Reference
+- Primary CTA: Brand Indigo (`#5e6ad2`)
+- Page Background: Marketing Black (`#08090a`)
+- Panel Background: Panel Dark (`#0f1011`)
+- Surface: Level 3 (`#191a1b`)
+- Heading text: Primary White (`#f7f8f8`)
+- Body text: Silver Gray (`#d0d6e0`)
+- Muted text: Tertiary Gray (`#8a8f98`)
+- Subtle text: Quaternary Gray (`#62666d`)
+- Accent: Violet (`#7170ff`)
+- Accent Hover: Light Violet (`#828fff`)
+- Border (default): `rgba(255,255,255,0.08)`
+- Border (subtle): `rgba(255,255,255,0.05)`
+- Focus ring: Multi-layer shadow stack
+
+### Example Component Prompts
+- "Create a hero section on `#08090a` background. Headline at 48px Inter Variable weight 510, line-height 1.00, letter-spacing -1.056px, color `#f7f8f8`, font-feature-settings `'cv01', 'ss03'`. Subtitle at 18px weight 400, line-height 1.60, color `#8a8f98`. Brand CTA button (`#5e6ad2`, 6px radius, 8px 16px padding) and ghost button (`rgba(255,255,255,0.02)` bg, `1px solid rgba(255,255,255,0.08)` border, 6px radius)."
+- "Design a card on dark background: `rgba(255,255,255,0.02)` background, `1px solid rgba(255,255,255,0.08)` border, 8px radius. Title at 20px Inter Variable weight 590, letter-spacing -0.24px, color `#f7f8f8`. Body at 15px weight 400, color `#8a8f98`, letter-spacing -0.165px."
+- "Build a pill badge: transparent background, `#d0d6e0` text, 9999px radius, 0px 10px padding, `1px solid #23252a` border, 12px Inter Variable weight 510."
+- "Create navigation: dark sticky header on `#0f1011`. Inter Variable 13px weight 510 for links, `#d0d6e0` text. Brand indigo CTA `#5e6ad2` right-aligned with 6px radius. Bottom border: `1px solid rgba(255,255,255,0.05)`."
+- "Design a command palette: `#191a1b` background, `1px solid rgba(255,255,255,0.08)` border, 12px radius, multi-layer shadow stack. Input at 16px Inter Variable weight 400, `#f7f8f8` text. Results list with 13px weight 510 labels in `#d0d6e0` and 12px metadata in `#62666d`."
+
+### Iteration Guide
+1. Always set font-feature-settings `"cv01", "ss03"` on all Inter text — this is non-negotiable for Linear's look
+2. Letter-spacing scales with font size: -1.584px at 72px, -1.056px at 48px, -0.704px at 32px, normal below 16px
+3. Three weights: 400 (read), 510 (emphasize/navigate), 590 (announce)
+4. Surface elevation via background opacity: `rgba(255,255,255, 0.02 → 0.04 → 0.05)` — never solid backgrounds on dark
+5. Brand indigo (`#5e6ad2` / `#7170ff`) is the only chromatic color — everything else is grayscale
+6. Borders are always semi-transparent white, never solid dark colors on dark backgrounds
+7. Berkeley Mono for any code or technical content, Inter Variable for everything else