# DESIGN.md: Duolingo-style design system

Measured from https://www.duolingo.com/ on 2026-10-14 by PikSpec (https://www.pikspec.com). An independent measurement of the rendered page, not Duolingo's official design system, and not affiliated with Duolingo.

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 duolingo.com, measured from the live site: it should feel designed by the same team as duolingo.com — the same temperament, colour, type and density — for a different product. Never use duolingo.com'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.duolingo.com/ — "www.duolingo.com" (home page).
- Page frame: a top navigation bar and a footer.
- It is type-led: no photography or illustration. Carry the page with typography, spacing and the colour roles.
- Interaction: 3 buttons on one page.
- The page runs about 9 screens long at 1440px wide.
- 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)
- Mostly neutral: 85% of the page is #FFFFFF and #100F3E and other neutrals; #58CC02 (4.5%) fills whole sections.
- #FF878D is an accent: 0.9% of the page, used for drawings only. Don't fill large areas with it.
- #1CB0F6 is an accent: 0.7% of the page, used for drawings only. Don't fill large areas with it.
- The largest type (48px feather) is bold (700).
- Very airy: text covers 3% of the page.
- Share of the painted page: #FFFFFF 65.6% (dominant, backgrounds); #000000 13.1% (supporting, drawings); #58CC02 4.5% (supporting, backgrounds); #100F3E 4.1% (supporting, backgrounds); #3D3D3D 0.9% (detail, drawings); #FF878D 0.9% (accent, drawings); #1CB0F6 0.7% (accent, drawings); #FFE700 0.6% (accent, drawings). Keep accents at these proportions; do not promote them to fills.
- Illustrations: 12 large illustrations in filled shapes, in #000000, #FFFFFF and #FFE700.
- Type as set (size, weight and tracking measured together; use these pairs): 48px weight 700; 32px weight 700; 19px weight 700; 17px weight 500; 15px weight 700; 14px weight 700.

1. DESIGN TOKENS — PASTE INTO YOUR GLOBAL CSS
Allowed colours, with how the original uses each. Use no other colour, including in hover states:
- #FFFFFF — 65.6% · backgrounds (var(--color-background))
- #000000 — 13.1% · drawings (var(--color-000000))
- #58CC02 — 4.5% · backgrounds (var(--color-positive))
- #100F3E — 4.1% · backgrounds (var(--color-100f3e))
- #3D3D3D — 0.9% · drawings (var(--color-3d3d3d))
- #FF878D — 0.9% · drawings (var(--color-ff878d))
- #1CB0F6 — 0.7% · drawings (var(--color-1cb0f6))
- #FFE700 — 0.6% · drawings (var(--color-ffe700))
- #B70070 — 0.4% · drawings (var(--color-b70070))
- #FFC700 — 0.4% · drawings (var(--color-ffc700))
- #FFAD00 — line drawings
- #FF8E00 — line drawings
- #66E1FF — line drawings
- #AFAFAF — small marks
- #3C3C3C — Text (var(--color-text))
- #777777 — Text muted (var(--color-text-muted))
- #A5ED6E — Border (var(--color-border))
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@500;700&display=swap");
@import url("https://fonts.googleapis.com/css2?family=Archivo:wght@700&display=swap");
```
Font: duolingo.com uses duolingo-sans (body) and feather (display) — its own licensed faces, not available to download. This kit uses Figtree for body and Archivo for display, the closest free matches, 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-text: #3C3C3C; /* Text */
  --color-text-muted: #777777; /* Text muted */
  --color-border: #A5ED6E; /* Border */
  --color-positive: #58CC02; /* Positive */
  --color-000000: #000000; /* 13.1% of the page, as drawings */
  --color-100f3e: #100F3E; /* 4.1% of the page, as fills */
  --color-3d3d3d: #3D3D3D; /* 0.9% of the page, as drawings */
  --color-ff878d: #FF878D; /* 0.9% of the page, as drawings */
  --color-1cb0f6: #1CB0F6; /* 0.7% of the page, as drawings */
  --color-ffe700: #FFE700; /* 0.6% of the page, as drawings */
  --color-b70070: #B70070; /* 0.4% of the page, as drawings */
  --color-ffc700: #FFC700; /* 0.4% of the page, as drawings */
  --color-e49e00: #E49E00; /* 0.3% of the page, as drawings */
  --color-89e219: #89E219; /* 0.3% of the page, as drawings */
  --font-body: duolingo-sans, "Figtree", sans-serif; /* duolingo-sans on the site; Figtree renders */
  --font-display: feather, "Archivo", sans-serif; /* feather on the site; Archivo renders */
  --type-display: 48px; /* Display, weight 700 */
  --type-display-leading: normal;
  --type-headline: 32px; /* Headline, weight 700 */
  --type-headline-leading: normal;
  --type-title: 19px; /* Title, weight 700 */
  --type-title-leading: 26.6px;
  --type-body-large: 17px; /* Body Large, weight 500 */
  --type-body-large-leading: 24px;
  --type-body-medium: 15px; /* Body Medium, weight 700 */
  --type-body-medium-leading: 22px;
  --type-body-small: 14px; /* Body Small, weight 700 */
  --type-body-small-leading: 17px;
  --type-label: 13px; /* Label, weight 700 */
  --type-label-leading: 16px;
  --space-2: 8px;
  --space-3: 12px;
  --space-4: 16px;
  --space-6: 24px;
  --space-8: 32px;
  --space-10: 40px;
  --space-12: 48px;
  --space-16: 64px;
  --space-24: 96px;
  --space-35: 140px;
  --radius-lg: 12px;
  --duration-1: 0.2s;
  --duration-2: 0.3s;
  --duration-3: 0.4s;
  --ease-1: cubic-bezier(0.22, 1, 0.36, 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-text: #3C3C3C;
  --color-text-muted: #777777;
  --color-border: #A5ED6E;
  --color-positive: #58CC02;
  --color-000000: #000000;
  --color-100f3e: #100F3E;
  --color-3d3d3d: #3D3D3D;
  --color-ff878d: #FF878D;
  --color-1cb0f6: #1CB0F6;
  --color-ffe700: #FFE700;
  --color-b70070: #B70070;
  --color-ffc700: #FFC700;
  --color-e49e00: #E49E00;
  --color-89e219: #89E219;
  --font-body: duolingo-sans, "Figtree", sans-serif;
  --font-display: feather, "Archivo", sans-serif;
  --text-display: 48px;
  --text-headline: 32px;
  --text-title: 19px;
  --text-title--line-height: 26.6px;
  --text-body-large: 17px;
  --text-body-large--line-height: 24px;
  --text-body-medium: 15px;
  --text-body-medium--line-height: 22px;
  --text-body-small: 14px;
  --text-body-small--line-height: 17px;
  --text-label: 13px;
  --text-label--line-height: 16px;
  --radius-lg: 12px;
  --ease-1: cubic-bezier(0.22, 1, 0.36, 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)", "text": "var(--color-text)", "text-muted": "var(--color-text-muted)", "border": "var(--color-border)", "positive": "var(--color-positive)" },
  fontFamily: { "body": ["var(--font-body)"], "display": ["var(--font-display)"] },
  borderRadius: { "lg": "var(--radius-lg)" },
}
```

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-display); margin: 0; }
a { color: inherit; }
:focus-visible { outline: 2px solid var(--color-text); outline-offset: 2px; }
```

3. COMPONENTS — MATCH THESE EXACTLY
```css
.link { /* Inline */
  background: transparent;
  min-height: 28px;
  color: var(--color-text-muted);
  font-family: var(--font-body);
  font-size: var(--type-body-large);
  font-weight: 500;
  line-height: 20px;
}
.link-2 { /* Strong */
  background: transparent;
  color: var(--color-1cb0f6);
  font-family: var(--font-body);
  font-size: var(--type-body-large);
  font-weight: 700;
  line-height: 24px;
}
.link-3 { /* Strong 2 */
  background: transparent;
  border-radius: var(--radius-lg);
  padding: 10px 14px 10px 14px;
  min-height: 63px;
  font-family: var(--font-body);
  font-size: var(--type-body-medium);
  font-weight: 700;
}
.nav { /* Default */
  background: transparent;
  min-height: 74px;
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--type-body-large);
  font-weight: 500;
  line-height: 20px;
}
.button { /* Tertiary */
  background: transparent;
  border-radius: var(--radius-lg);
  padding: 0px 16px 0px 16px;
  min-height: 50px;
  color: var(--color-1cb0f6);
  font-family: var(--font-body);
  font-size: var(--type-body-medium);
  font-weight: 700;
}
.button-2 { /* Tertiary 2 */
  background: transparent;
  color: #AFAFAF;
  font-family: var(--font-body);
  font-size: var(--type-body-medium);
  font-weight: 700;
  line-height: 17.25px;
}
```
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.
- The opening screen carries a large image or video on the left. Leave a [content: hero image or video] slot there, at least half the screen wide; the opening is not text alone.
- Sections change ground between #DDF4FF, #100F3E and Positive (#58CC02); use only those.
- Type: Figtree (standing in for duolingo-sans) for body; Archivo (standing in for feather) for display. Hierarchy comes from size and weight, not colour or decoration.
- Everything sits on a 4px grid.
- Corner radii are 12px — nothing else.
- The system is flat: no drop shadows.
- Body text uses duolingo-sans at around 17px, weights 500, 700.
- Headings use feather; the largest heading is 48px.
- Corner radii in use: 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, 15px gap, centred 32px heading (weight 700) set mid-band, artwork on the left.
2. Text (×4) — 4 bands of 530px, left-aligned 48px heading (weight 700) set mid-band, artwork on the right.
3. Split — 1289px tall, 2 equal columns, 24px gap, centred 64px heading (weight 700), artwork behind the content.
4. Statement — 900px tall, centred 15px heading (weight 700) set low in the band, artwork on the left, on #100F3E.
5. Text — 722px tall, left-aligned 48px heading (weight 700) set mid-band, artwork on the right.
6. Full-bleed image — 853px tall, centred 64px heading (weight 700), artwork behind the content.
7. Footer — 827px tall, split 3 / 3 / 2 / 2 / 2, 24px gap, left-aligned 19px heading (weight 700), on #58CC02.
- Content sits in a 988px container, 226px from the edge at 1440px wide.
- The hero is 900px (exactly one screen): 2 equal columns, 15px gap, centred 32px heading (weight 700) set mid-band, artwork on the left.
- Column splits on a 12-column grid: halves (2×), 3/3/2/2/2; gaps of 24px.
- Headings mix left (3) and centred (4) alignment.
- Sections change background 3 times, between #100F3E, #58CC02: colour comes in full-width bands, not in boxes.
- A typical section is about 853px tall.

COPY SHAPE (MATCH THE LENGTH AND CASE; WRITE YOUR OWN WORDS)
- The main heading is 10 words long.
- Section headings are short: typically 3 words.
- Headings are all lower 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 988px wide, centred, with var(--space-4) (16px) side padding on small screens.
- The largest heading scales fluidly: font-size: clamp(19px, 3.3vw, 48px). 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 (11:1) and Text muted on Background (4.5:1).
- 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)
- No drop shadows anywhere, including cards, buttons and images. (No box-shadow was measured on the page.)
- No gradients: not in backgrounds, text, buttons or borders. (No gradient was measured.)
- Only these colours: #FFFFFF, #000000, #58CC02, #100F3E, #3D3D3D, #FF878D, #1CB0F6, #FFE700, #B70070, #FFC700, #FFAD00, #FF8E00, #66E1FF, #AFAFAF, #3C3C3C, #777777, #A5ED6E. 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.)
- #FF878D only for drawings — never as a section background or a large panel. (It covers 0.9% of the page.)
- #1CB0F6 only for drawings — never as a section background or a large panel. (It covers 0.7% of the page.)
- Only the fonts in the tokens: Figtree for body; Archivo for display. No other typeface, and no Inter, Roboto or system UI font unless it is one of these. (The page is set in feather and duolingo-sans; the tokens carry what stands in for them.)
- Headings and large text never heavier than weight 700. Do not make headlines bold to add emphasis. (Every size from 24px up is set at weight 700 or lighter.)
- 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.)
- Build the sections your product needs, not the original's list. Give each one this system's look: its kinds of section (hero, text, split, statement, image, footer), 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 duolingo.com'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 box-shadow and filter: drop-shadow. There should be none.
- 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.
- #FF878D covers about 0.9% of the page or less, as on the original.
- #1CB0F6 covers about 0.7% of the page or less, as on the original.
- No text 24px or larger has a font-weight above 700.
- Every section, including ones the original does not have, uses only this system's colours, type, shapes and spacing.
- Content sits in a 988px container with 226px side margins at 1440px.
- 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.