# DESIGN.md: Perplexity-style design system

Measured from https://www.perplexity.ai/ on 2026-10-15 by PikSpec (https://www.pikspec.com). An independent measurement of the rendered page, not Perplexity's official design system, and not affiliated with Perplexity.

Use it to build your own product in this design language: put this file in your project root and tell your AI tool (Claude Code, Cursor, Codex, Lovable, v0) to follow DESIGN.md. Never use the original's name, logo, copy or images; licensed fonts are replaced with the closest free Google Fonts.

To capture any other page, or get a ready project for your tool: https://www.pikspec.com/build-with-ai

HOW IT SHOULD LOOK
Build it in the design language of perplexity.ai, measured from the live site: it should feel designed by the same team as perplexity.ai — the same temperament, colour, type and density — for a different product. Never use perplexity.ai's name, logo, words or images.

Stack: use the one your project already has. Starting fresh: React + Vite + TypeScript + Tailwind CSS v4, with no UI kit (no shadcn/ui, MUI or Chakra) — their defaults would override this system. In a chat that shows one file (an artifact or canvas), build one HTML file instead, with the tokens below in its <style> block.
Use every value exactly as written. Do not round, rename, approximate or substitute a colour, size, radius, shadow or easing (fonts: see section 1). Anything not listed here does not exist in this system.

THE WEBSITE THIS SYSTEM COMES FROM
- Reference page: https://www.perplexity.ai/ — "www.perplexity.ai" (home page).
- Page frame: a top navigation bar and a persistent side panel beside the content. This is a tool- or docs-style layout, not a marketing page of stacked full-width bands.
- Content is grouped in cards (2 on the page, up to 2 side by side). Keep cards for grouped content only, not for every section.
- It uses 1 image. Images are supporting, not the hero — keep them small and purposeful.
- Interaction: 21 buttons and 1 form field on one page.
- Density is high: lots of information per screen, tight spacing steps used often.

HOW IT LOOKS (WHAT MAKES IT LOOK LIKE ITSELF, BEYOND THE VALUES)
- Almost entirely neutral: 99% of the page is painted in #FBFBFB and #FFFFFF.
- #016A71 is an accent: under 0.1% of the page, as small fills such as buttons and badges. Keep it to small areas.
- The largest type (24px pplxSans) is regular weight, not bold (400).
- Balanced: text covers 12% of the page.
- Share of the painted page: #FBFBFB 94% (dominant, backgrounds); #0B2833 2.5% (supporting, text); #FFFFFF 2% (detail, backgrounds); #000000 1.5% (supporting, text); #252525 0.1% (detail, backgrounds). Keep accents at these proportions; do not promote them to fills.
- Hairline dividers: 1px lines in #0B2833 separate sections and rows (5 of them).
- Type as set (size, weight and tracking measured together; use these pairs): 24px weight 400; 16px weight 400; 14px weight 400; 12px weight 400; 11px weight 500.

1. DESIGN TOKENS — PASTE INTO YOUR GLOBAL CSS
Allowed colours, with how the original uses each. Use no other colour, including in hover states:
- #FBFBFB — 94% · backgrounds (var(--color-fbfbfb))
- #0B2833 — 2.5% · text (var(--color-text-muted))
- #FFFFFF — 2% · backgrounds (var(--color-background))
- #000000 — 1.5% · text (var(--color-text))
- #252525 — 0.1% · backgrounds
- #FCFCF9 — Surface (var(--color-surface))
- #016A71 — Positive (var(--color-positive))
Fonts — put these first in your global CSS (one import per font, so one that fails cannot stop the others):
```css
@import url("https://fonts.googleapis.com/css2?family=Figtree:wght@400;500&display=swap");
```
Font: perplexity.ai uses pplxSans (body) — its own licensed face, not available to download. This kit uses Figtree for body, the closest free match, already in the tokens. If you own the original, add it with @font-face and it is used first; to use another font, change the --font-* variables.
Keep every size, weight, line height and tracking exactly as listed whichever font renders.
```css
:root {
  --color-background: #FFFFFF; /* Background */
  --color-surface: #FCFCF9; /* Surface */
  --color-text: #000000; /* Text */
  --color-text-muted: #0B2833; /* Text muted */
  --color-positive: #016A71; /* Positive */
  --color-fbfbfb: #FBFBFB; /* 94% of the page, as fills */
  --font-body: "pplxSans", "Figtree", sans-serif; /* pplxSans on the site; Figtree renders */
  --type-headline: 24px; /* Headline, weight 400 */
  --type-headline-leading: 32px;
  --type-body-large: 16px; /* Body Large, weight 400 */
  --type-body-large-leading: 24px;
  --type-body-small: 14px; /* Body Small, weight 400 */
  --type-body-small-leading: 20px;
  --type-label-large: 12px; /* Label Large, weight 400 */
  --type-label-large-leading: 16px;
  --type-label-small: 11px; /* Label Small, weight 500 */
  --type-label-small-leading: 11px;
  --space-1: 4px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-8: 32px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --radius-xl: 11px;
  --radius-2xl: 12px;
  --radius-3xl: 15px;
  --radius-full: 9999px;
  --radius-16: 16px; /* component radius */
  --elevation-1: rgba(0, 0, 0, 0) 0px 0px 0px 0px, rgba(0, 0, 0, 0) 0px 0px 0px 0px, color(srgb 0.0431373 0.156863 0.2 / 0.05) 0px 0px 0px 1px, color(srgb 0.0431373 0.156863 0.2 / 0.00999999) 0px 1px 0px 0px, color(srgb 0.0431373 0.156863 0.2 / 0.05) 0px 1px 1px 0px, color(srgb 0.0431373 0.156863 0.2 / 0.08) 0px 0px 2px 0px, color(srgb 0.0431373 0.156863 0.2 / 0.08) 0px 2px 6px -2px;
  --elevation-2: color(srgb 0.00392157 0.415686 0.443137 / 0) 0px 0px 36px 4px;
  --duration-1: 0.075s;
  --duration-2: 0.15s;
  --duration-3: 0.3s;
  --ease-1: cubic-bezier(0, 0, 0.2, 1);
  --ease-2: cubic-bezier(0.4, 0, 0.2, 1);
}
```
Tailwind CSS v4 (the default for new projects): put this after `@import "tailwindcss";`. It removes Tailwind's own palette, so only these colours exist as utilities:
```css
@theme {
  --color-*: initial;
  --color-background: #FFFFFF;
  --color-surface: #FCFCF9;
  --color-text: #000000;
  --color-text-muted: #0B2833;
  --color-positive: #016A71;
  --color-fbfbfb: #FBFBFB;
  --font-body: "pplxSans", "Figtree", sans-serif;
  --text-headline: 24px;
  --text-headline--line-height: 32px;
  --text-body-large: 16px;
  --text-body-large--line-height: 24px;
  --text-body-small: 14px;
  --text-body-small--line-height: 20px;
  --text-label-large: 12px;
  --text-label-large--line-height: 16px;
  --text-label-small: 11px;
  --text-label-small--line-height: 11px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --radius-xl: 11px;
  --radius-2xl: 12px;
  --radius-3xl: 15px;
  --radius-full: 9999px;
  --shadow-e1: rgba(0, 0, 0, 0) 0px 0px 0px 0px, rgba(0, 0, 0, 0) 0px 0px 0px 0px, color(srgb 0.0431373 0.156863 0.2 / 0.05) 0px 0px 0px 1px, color(srgb 0.0431373 0.156863 0.2 / 0.00999999) 0px 1px 0px 0px, color(srgb 0.0431373 0.156863 0.2 / 0.05) 0px 1px 1px 0px, color(srgb 0.0431373 0.156863 0.2 / 0.08) 0px 0px 2px 0px, color(srgb 0.0431373 0.156863 0.2 / 0.08) 0px 2px 6px -2px;
  --shadow-e2: color(srgb 0.00392157 0.415686 0.443137 / 0) 0px 0px 36px 4px;
  --ease-1: cubic-bezier(0, 0, 0.2, 1);
  --ease-2: cubic-bezier(0.4, 0, 0.2, 1);
}
```
Tailwind CSS v3 only: extend the theme with these instead, and use no other palette:
```js
// tailwind.config — theme.extend
{
  colors: { "background": "var(--color-background)", "surface": "var(--color-surface)", "text": "var(--color-text)", "text-muted": "var(--color-text-muted)", "positive": "var(--color-positive)" },
  fontFamily: { "body": ["var(--font-body)"] },
  borderRadius: { "md": "var(--radius-md)", "lg": "var(--radius-lg)", "xl": "var(--radius-xl)", "2xl": "var(--radius-2xl)", "3xl": "var(--radius-3xl)", "full": "var(--radius-full)" },
  boxShadow: { "e1": "var(--elevation-1)", "e2": "var(--elevation-2)" },
}
```

2. BASE STYLES
```css
html { background: var(--color-background); }
body { margin: 0; font-family: var(--font-body); font-size: var(--type-body-large); line-height: var(--type-body-large-leading); color: var(--color-text); -webkit-font-smoothing: antialiased; -moz-osx-font-smoothing: grayscale; }
h1, h2, h3 { font-family: var(--font-body); margin: 0; }
a { color: inherit; }
:focus-visible { outline: 2px solid var(--color-text); outline-offset: 2px; }
```

3. COMPONENTS — MATCH THESE EXACTLY
```css
.card { /* Default */
  background: var(--color-background);
  border-radius: var(--radius-16);
  min-height: 118px;
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--type-body-large);
  font-weight: 400;
  line-height: 24px;
}
.card-2 { /* Alternative 1 */
  background: var(--color-background);
  border-radius: 0px 0px 16px 16px;
  padding: 12px 0px 0px 0px;
  min-height: 117px;
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--type-body-large);
  font-weight: 400;
  line-height: 24px;
}
.button { /* Tertiary */
  background: transparent;
  border-radius: var(--radius-xl);
  padding: var(--space-4);
  min-height: 88px;
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--type-body-large);
  font-weight: 400;
  line-height: 24px;
  /* recorded states: focus */
}
.button-2 { /* Tertiary 2 */
  background: transparent;
  border-radius: var(--radius-lg);
  min-height: 40px;
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--type-body-large);
  font-weight: 400;
  line-height: 24px;
  /* recorded states: focus */
}
.button-3 { /* Tertiary 3 */
  background: transparent;
  border-radius: var(--radius-full);
  padding: 0px 12px 0px 8px;
  min-height: 32px;
  color: var(--color-text-muted);
  font-family: var(--font-body);
  font-size: var(--type-body-small);
  font-weight: 400;
  line-height: 20px;
  /* recorded states: focus, hover */
}
.link { /* Inline */
  background: transparent;
  border-radius: var(--radius-lg);
  min-height: 40px;
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--type-body-large);
  font-weight: 400;
  line-height: 24px;
  /* recorded states: focus */
}
.input { /* Default */
  background: transparent;
  min-height: 52px;
  color: var(--color-text-muted);
  font-family: var(--font-body);
  font-size: var(--type-body-large);
  font-weight: 400;
  line-height: 24px;
}
```
Where a component lists recorded states, write those states using only the colours above; the capture saw that the state exists, not its values. Never invent a state colour.

4. PAGE COMPOSITION
- Light interface on #FFFFFF. Keep that ground; do not add a dark mode or alternate section backgrounds the system does not have.
- Type: Figtree (standing in for pplxSans) for body. Hierarchy comes from size and weight, not colour or decoration.
- Everything sits on a 4px grid.
- Corner radii are 6px, 8px, 11px, 12px, 15px, fully round (pill) — nothing else.
- Body text uses pplxSans at around 16px, weights 400, 500.
- Cards use 16px corners.
- Corner radii in use: 9999px (pill), 8px, 6px, 16px, 12px.

HOW THE ORIGINAL PACES ITS PAGE (BORROW THE RHYTHM — THE OPENING, THE COLOURED BANDS, THE CARD GRIDS — NOT THE LIST; BUILD THE SECTIONS YOUR PRODUCT NEEDS)
1. Hero — 900px tall, 2 equal columns, 12px gap, left-aligned 24px heading (weight 400) set mid-band.
- The hero is 900px (exactly one screen): 2 equal columns, 12px gap, left-aligned 24px heading (weight 400) set mid-band.
- Column splits on a 12-column grid: halves; gaps of 12px.
- Sections share one background; they are separated by space and lines, not colour bands.

COPY SHAPE (MATCH THE LENGTH AND CASE; WRITE YOUR OWN WORDS)
- The page has no single main heading.
- Section headings are short: typically 2 words.
- Headings are in Title Case.
- The page describes itself in about 17 words; keep your intro paragraph to about that length.

5. MOTION
Interactive elements change colour, background, border and opacity with the measured timing. Animate nothing else.
```css
a, button, [role="button"], input { transition: color var(--duration-1) var(--ease-1), background-color var(--duration-1) var(--ease-1), border-color var(--duration-1) var(--ease-1), opacity var(--duration-1) var(--ease-1); }
@media (prefers-reduced-motion: reduce) {
  *, *::before, *::after { animation-duration: 0.01ms !important; animation-iteration-count: 1 !important; transition-duration: 0.01ms !important; scroll-behavior: auto !important; }
}
```
No scroll-triggered fade-ins, parallax, typewriter text or bouncing elements.

6. RESPONSIVE
- The design was measured at 1440px wide. Lay it out for that width first, then let it reflow down to 360px.
- Content sits in a column at most 416px wide, centred, with var(--space-4) (16px) side padding on small screens.
- The largest heading scales fluidly: font-size: clamp(14px, 1.7vw, 24px). Every other size stays fixed.
- Break on composition, not device names: a row of columns drops a column when any column would be narrower than 240px; side-by-side splits stack when either side would be narrower than 320px.
- Spacing steps never change between sizes; use smaller steps from the same list where space is tight.
- On touch screens, every link and button has a hit area of at least 44 × 44px without changing its drawn size.

7. ACCESSIBILITY
- Text pairs that pass for body copy: Text on Background (21:1), Text muted on Background (15.4:1), Positive on Background (6.4:1), Text on Surface (20.4:1), Text muted on Surface (15:1) and Positive on Surface (6.2:1).
- Use no other text-on-background pairing.
- One h1 per page, headings in order, landmarks (header, nav, main, footer), real buttons and links, a label on every field, alt text on every image, an aria-label on icon-only buttons.
- Every interactive element shows the :focus-visible outline above.

8. DO NOT (THESE ARE WHAT MAKE AI-BUILT SITES LOOK GENERIC)
- Only the two shadows in the tokens, on the components that use them. (2 shadow values were measured; inventing softer ones changes the depth of the page.)
- No gradients: not in backgrounds, text, buttons or borders. (No gradient was measured.)
- Only these colours: #FBFBFB, #0B2833, #FFFFFF, #000000, #252525, #FCFCF9, #016A71. No new tints, no Tailwind defaults (slate, indigo, violet). (They are every colour that covers a measurable part of the page, and the colours its lines and drawings use.)
- #016A71 only as small fills (buttons, badges) — never a section background or a large panel. (It covers under 0.1% of the page.)
- Only the fonts in the tokens: Figtree for body. No other typeface, and no Inter, Roboto or system UI font unless it is one of these. (The page is set in pplxSans; the tokens carry what stands in for them.)
- Headings and large text never heavier than weight 400. Do not make headlines bold to add emphasis. (Every size from 24px up is set at weight 400 or lighter.)
- No all-caps eyebrow labels above headings. (No uppercase text was measured.)
- No stock photography or AI-generated photos. (Photographs cover almost none of the page.)
- No icon above every feature, no emoji, no decorative blobs, sparkles or glows. (None of these is part of the captured design; they are a coding model's defaults.)
- The hero is left-aligned. Do not centre it. (The captured hero sets its heading on the left.)
- Build the sections your product needs, not the original's list. Give each one this system's look: its kinds of section (hero), its colours, type, shapes and spacing. (The style carries to any kind of site; the original's page was for a different product.)
- No glassmorphism, backdrop blur, glowing orbs, noise blobs or neon outlines.
- No row of three identical feature cards as the default section. Vary the layout from section to section: a split, a list, a single large statement, a table.
- No centred-everything hero with a pill badge, a gradient headline and two buttons. Lead with the most specific thing about the product.
- No filler copy: no "Unlock your potential", "Revolutionize", "Seamless", "Elevate", "Supercharge", "Next-gen" or lorem ipsum. Write plain, specific sentences a real company would publish.
- No made-up statistics, testimonials or customer logos. Leave a clearly marked [content: …] slot instead.
- No radius larger than the largest one listed.
- Do not use perplexity.ai's name, logo, copy or images. This is its design system, not its content.

BEFORE YOU FINISH
- Search your code for every colour, font size, spacing value, radius, shadow and easing, and replace anything that is not a variable above.
- Check that no [content: …] slot has been filled with invented facts.
- Search your CSS for gradient(. There should be none.
- Every colour value in your CSS is one of the allowed colours. Nothing else, including in hover states.
- #016A71 covers about 0.1% of the page or less, as on the original.
- No text 24px or larger has a font-weight above 400.
- Every section, including ones the original does not have, uses only this system's colours, type, shapes and spacing.
- There is no placeholder copy (lorem ipsum, "Feature one", "Your headline here"). Every word is real.
- Take a screenshot at 1440px and put it beside the original. List every difference in colour, weight, spacing, alignment and imagery, and fix each before finishing. Then check 390px wide: nothing scrolls sideways and no heading runs off the screen.