# DESIGN.md: Trello-style design system

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

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 trello.com, measured from the live site: it should feel designed by the same team as trello.com — the same temperament, colour, type and density — for a different product. Never use trello.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://trello.com/ — "trello.com" (home page).
- Page frame: a top navigation bar and a footer.
- Content is grouped in cards (5 on the page, up to 3 side by side). Keep cards for grouped content only, not for every section.
- It uses 74 images including 1 video, 53 of them large. Large, real product imagery is part of the look — leave clearly labelled image slots at those sizes rather than stock photos or abstract 3D shapes.
- Interaction: 22 buttons and 3 form fields on one page.
- The page runs about 5 screens long at 1440px wide.
- Density is low: few elements per screen, generous space around each one.

HOW IT LOOKS (WHAT MAKES IT LOOK LIKE ITSELF, BEYOND THE VALUES)
- Mostly neutral: 83% of the page is #FFFFFF and #F4F5F7 and other neutrals; #0065FF (9.3%) fills whole sections.
- #091E42 is an accent: 4% of the page, used for text and small fills such as buttons. Don't fill large areas with it.
- #172B4D is an accent: 2.3% of the page, as one of a few coloured bands or panels. Use it for a band or two, never as the page ground.
- The largest type (48px Charlie Display) is medium weight, not bold (500).
- Open: text covers 12% of the page.
- Share of the painted page: #FFFFFF 66.1% (dominant, backgrounds); #F4F5F7 11.3% (supporting, backgrounds); #0065FF 9.3% (supporting, backgrounds); #091E42 4% (accent, text); #FAFBFC 2.7% (detail, backgrounds); #DEEBFF 2.5% (detail, backgrounds); #172B4D 2.3% (accent, backgrounds); #0747A6 1.2% (accent, backgrounds). Keep accents at these proportions; do not promote them to fills.
- Hairline dividers: 1px lines in #0065FF separate sections and rows (15 of them).
- Large images: Photographs, video or raster artwork cover about 32% of the page.
- Type as set (size, weight and tracking measured together; use these pairs): 48px weight 500; 36px weight 500; 24px weight 400; 20px weight 400; 19.2px weight 400; 16px weight 400.

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 — 66.1% · backgrounds (var(--color-surface))
- #F4F5F7 — 11.3% · backgrounds (var(--color-background))
- #0065FF — 9.3% · backgrounds (var(--color-0065ff))
- #091E42 — 4% · text (var(--color-text))
- #FAFBFC — 2.7% · backgrounds (var(--color-fafbfc))
- #DEEBFF — 2.5% · backgrounds (var(--color-deebff))
- #172B4D — 2.3% · backgrounds (var(--color-172b4d))
- #0747A6 — 1.2% · backgrounds (var(--color-0747a6))
- #F0F0F0 — 0.3% · backgrounds (var(--color-f0f0f0))
- #0052CC — 0.2% · text
- #DFE1E6 — hairlines and grid lines (var(--color-border))
- #505F79 — hairlines and grid lines (var(--color-text-muted))
- #00C7E5 — Positive (var(--color-positive))
- #FFAB00 — Warning (var(--color-warning))
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;600;700&display=swap");
@import url("https://fonts.googleapis.com/css2?family=Archivo:wght@500;700&display=swap");
```
Font: trello.com uses Charlie Text (body) and Charlie Display (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: #F4F5F7; /* Background */
  --color-surface: #FFFFFF; /* Surface */
  --color-text: #091E42; /* Text */
  --color-text-muted: #505F79; /* Text muted */
  --color-border: #DFE1E6; /* Border */
  --color-action: #091E42; /* Action */
  --color-on-action: #FFFFFF; /* On action */
  --color-link: #091E42; /* Link */
  --color-positive: #00C7E5; /* Positive */
  --color-warning: #FFAB00; /* Warning */
  --color-0065ff: #0065FF; /* 9.3% of the page, as fills */
  --color-fafbfc: #FAFBFC; /* 2.7% of the page, as fills */
  --color-deebff: #DEEBFF; /* 2.5% of the page, as fills */
  --color-172b4d: #172B4D; /* 2.3% of the page, as fills */
  --color-0747a6: #0747A6; /* 1.2% of the page, as fills */
  --color-f0f0f0: #F0F0F0; /* 0.3% of the page, as fills */
  --font-body: "Charlie Text", "Figtree", sans-serif; /* Charlie Text on the site; Figtree renders */
  --font-display: "Charlie Display", "Archivo", sans-serif; /* Charlie Display on the site; Archivo renders */
  --type-display-large: 48px; /* Display Large, weight 500 */
  --type-display-large-leading: 60px;
  --type-display-small: 36px; /* Display Small, weight 500 */
  --type-display-small-leading: 48px;
  --type-headline: 24px; /* Headline, weight 400 */
  --type-headline-leading: 36px;
  --type-title-large: 20px; /* Title Large, weight 400 */
  --type-title-large-leading: 30px;
  --type-title-small: 19.2px; /* Title Small, weight 400 */
  --type-title-small-leading: 28.8px;
  --type-body: 16px; /* Body, weight 400 */
  --type-body-leading: 24px;
  --type-label: 12px; /* Label, weight 400 */
  --type-label-leading: 16px;
  --space-4: 4px;
  --space-8: 8px;
  --space-12: 12px;
  --space-16: 16px;
  --space-20: 20px;
  --space-24: 24px;
  --space-32: 32px;
  --space-40: 40px;
  --space-48: 48px;
  --space-52: 52px;
  --space-60: 60px;
  --space-76: 76px;
  --space-80: 80px;
  --space-128: 128px;
  --space-192: 192px;
  --radius-xs: 1px;
  --radius-sm: 2px;
  --radius-md: 3px;
  --radius-lg: 4px;
  --radius-xl: 4.8px;
  --radius-2xl: 8px;
  --radius-3xl: 17px;
  --elevation-1: rgba(9, 30, 66, 0.2) 0px 3px 5px 0px, rgba(9, 30, 66, 0.31) 0px 0px 1px 0px;
  --elevation-2: rgb(199, 197, 199) 0px 0px 12px 2px;
  --elevation-3: rgba(9, 30, 66, 0.15) 0px 8px 16px 0px;
  --elevation-4: rgba(9, 30, 66, 0.15) 0px 24px 16px -16px inset;
  --duration-1: 0.25s;
  --duration-2: 0.3s;
  --duration-3: 0.5s;
  --ease-1: ease-out;
}
```
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: #F4F5F7;
  --color-surface: #FFFFFF;
  --color-text: #091E42;
  --color-text-muted: #505F79;
  --color-border: #DFE1E6;
  --color-action: #091E42;
  --color-on-action: #FFFFFF;
  --color-link: #091E42;
  --color-positive: #00C7E5;
  --color-warning: #FFAB00;
  --color-0065ff: #0065FF;
  --color-fafbfc: #FAFBFC;
  --color-deebff: #DEEBFF;
  --color-172b4d: #172B4D;
  --color-0747a6: #0747A6;
  --color-f0f0f0: #F0F0F0;
  --font-body: "Charlie Text", "Figtree", sans-serif;
  --font-display: "Charlie Display", "Archivo", sans-serif;
  --text-display-large: 48px;
  --text-display-large--line-height: 60px;
  --text-display-small: 36px;
  --text-display-small--line-height: 48px;
  --text-headline: 24px;
  --text-headline--line-height: 36px;
  --text-title-large: 20px;
  --text-title-large--line-height: 30px;
  --text-title-small: 19.2px;
  --text-title-small--line-height: 28.8px;
  --text-body: 16px;
  --text-body--line-height: 24px;
  --text-label: 12px;
  --text-label--line-height: 16px;
  --radius-xs: 1px;
  --radius-sm: 2px;
  --radius-md: 3px;
  --radius-lg: 4px;
  --radius-xl: 4.8px;
  --radius-2xl: 8px;
  --radius-3xl: 17px;
  --shadow-e1: rgba(9, 30, 66, 0.2) 0px 3px 5px 0px, rgba(9, 30, 66, 0.31) 0px 0px 1px 0px;
  --shadow-e2: rgb(199, 197, 199) 0px 0px 12px 2px;
  --shadow-e3: rgba(9, 30, 66, 0.15) 0px 8px 16px 0px;
  --shadow-e4: rgba(9, 30, 66, 0.15) 0px 24px 16px -16px inset;
  --ease-1: ease-out;
}
```
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)", "border": "var(--color-border)", "action": "var(--color-action)", "on-action": "var(--color-on-action)", "link": "var(--color-link)", "positive": "var(--color-positive)", "warning": "var(--color-warning)" },
  fontFamily: { "body": ["var(--font-body)"], "display": ["var(--font-display)"] },
  borderRadius: { "xs": "var(--radius-xs)", "sm": "var(--radius-sm)", "md": "var(--radius-md)", "lg": "var(--radius-lg)", "xl": "var(--radius-xl)", "2xl": "var(--radius-2xl)", "3xl": "var(--radius-3xl)" },
  boxShadow: { "e1": "var(--elevation-1)", "e2": "var(--elevation-2)", "e3": "var(--elevation-3)", "e4": "var(--elevation-4)" },
}
```

2. BASE STYLES
```css
html { background: var(--color-background); }
body { margin: 0; font-family: var(--font-body); 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: var(--color-link); }
:focus-visible { outline: 2px solid var(--color-action); outline-offset: 2px; }
```

3. COMPONENTS — MATCH THESE EXACTLY
```css
.card { /* Default */
  background: var(--color-surface);
  border-radius: var(--radius-2xl);
  min-height: 472px;
  box-shadow: var(--elevation-1);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--type-body);
  font-weight: 400;
  line-height: 24px;
  /* recorded states: focus */
}
.card-2 { /* Alternative 1 */
  background: var(--color-surface);
  border-radius: var(--radius-2xl);
  padding: var(--space-32);
  min-height: 364px;
  box-shadow: var(--elevation-3);
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--type-title-large);
  font-weight: 400;
  line-height: 30px;
  /* recorded states: focus */
}
.button { /* Primary */
  background: var(--color-action);
  border: 1px solid #0065FF;
  border-radius: var(--radius-xl);
  padding: 11px 16px 13px 16px;
  min-height: 50px;
  color: var(--color-on-action);
  font-family: var(--font-body);
  font-size: var(--type-body);
  font-weight: 400;
  line-height: 24px;
  /* recorded states: focus, hover, active */
}
.button-2 { /* Secondary */
  background: var(--color-172b4d);
  border: 1px solid #172B4D;
  border-radius: var(--radius-xl);
  padding: 8px 20px 8px 20px;
  color: #FFFFFF;
  font-family: var(--font-body);
  font-size: var(--type-body);
  font-weight: 400;
  line-height: 24px;
  /* recorded states: focus, hover, active */
}
.button-3 { /* Secondary 2 */
  background: var(--color-surface);
  border: 1px solid #0065FF;
  border-radius: var(--radius-xl);
  padding: 11px 16px 13px 16px;
  min-height: 50px;
  color: #0052CC;
  font-family: var(--font-body);
  font-size: var(--type-body);
  font-weight: 400;
  line-height: 24px;
  /* recorded states: hover, focus, active */
}
.link { /* Inline */
  background: transparent;
  color: #0052CC;
  font-family: var(--font-body);
  font-size: var(--type-body);
  font-weight: 400;
  line-height: 24px;
  /* recorded states: hover, focus */
}
.link-2 { /* Inline 2 */
  background: transparent;
  padding: 20px 16px 16px 16px;
  min-height: 60px;
  color: var(--color-172b4d);
  font-family: var(--font-body);
  font-size: var(--type-body);
  font-weight: 400;
  line-height: 24px;
  /* recorded states: hover, focus */
}
.link-3 { /* Inline 3 */
  background: transparent;
  padding: var(--space-16);
  min-height: 60px;
  color: var(--color-text);
  font-family: var(--font-body);
  font-size: var(--type-title-large);
  font-weight: 400;
  line-height: 30px;
  /* recorded states: hover, focus */
}
.input { /* Default */
  background: var(--color-surface);
  border: 1px solid var(--color-border);
  border-radius: var(--radius-xl);
  padding: 11px 12px 13px 12px;
  min-height: 50px;
  font-family: var(--font-body);
  font-size: var(--type-body);
  font-weight: 400;
  line-height: 24px;
  /* recorded states: focus */
}
```
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 #F4F5F7. Keep that ground; do not add a dark mode.
- The opening screen carries a large image or video beside the heading. 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 Surface (#FFFFFF), #DEEBFF, Background (#F4F5F7) and #0065FF; use only those.
- #091E42 is the action colour. Fill the primary action with it and little else — at most one #091E42-filled element per screen; other accents keep to the uses listed above.
- Type: Figtree (standing in for Charlie Text) for body; Archivo (standing in for Charlie Display) for display. Hierarchy comes from size and weight, not colour or decoration.
- Corner radii are 1px, 2px, 3px, 4px, 4.8px, 8px, 17px — nothing else.
- Body text uses Charlie Text at around 16px, weights 400, 500, 600, 700.
- Headings use Charlie Display; the largest heading is 48px.
- Primary buttons are #091E42, 4px radius, weight 400.
- Cards use 8px corners with a soft shadow.
- Corner radii in use: 4.8px, 2px, 4px, 8px, 1px.

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 — 144px tall, centred 16px heading (weight 400) set low in the band, on #DEEBFF.
2. Hero — 809px tall, 2 equal columns, left-aligned 48px heading (weight 500), image on the right, on #F4F5F7.
3. Cards — 796px tall, 3 equal columns, 16px gap, left-aligned 20px heading (weight 400), image centred.
4. Split — 932px tall, split 7 / 5, 32px gap, centred 36px heading (weight 700), on #0065FF.
5. Text — 163px tall, left-aligned 20px heading (weight 400).
6. Cards — 419px tall, 3 equal columns, left-aligned 24px heading (weight 500).
7. Cards — 567px tall, 3 equal columns, 16px gap, left-aligned 36px heading (weight 500).
8. Statement — 226px tall, centred 20px heading (weight 400), image centred.
9. Statement — 356px tall, centred 36px heading (weight 500), on #F4F5F7.
10. Footer — 229px tall, split 2 / 10, centred 16px heading (weight 400), on #172B4D.
- Content sits in a 1140px container, 190px from the edge at 1440px wide.
- The hero is 144px (0.2 screens): centred 16px heading (weight 400) set low in the band, on #DEEBFF.
- Column splits on a 12-column grid: thirds (3×), halves, 7/5, 2/10; gaps of 16px.
- Headings mix left (5) and centred (5) alignment.
- Sections change background 6 times, between #DEEBFF, #F4F5F7, #0065FF: colour comes in full-width bands, not in boxes.
- A typical section is about 419px tall.

COPY SHAPE (MATCH THE LENGTH AND CASE; WRITE YOUR OWN WORDS)
- The main heading is 8 words long.
- Section headings are medium length: typically 5 words.
- Headings are in sentence case (only the first word capitalised).
- The page describes itself in about 29 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 1140px wide, centred, with var(--space-16) (16px) side padding on small screens.
- The largest heading scales fluidly: font-size: clamp(24px, 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 (15.1:1), Text muted on Background (5.9:1), Action on Background (15.1:1), Link on Background (15.1:1), Text on Surface (16.5:1), Text muted on Surface (6.5:1), Action on Surface (16.5:1), Link on Surface (16.5:1) and On action on Action (16.5:1).
- 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 gradients: not in backgrounds, text, buttons or borders. (No gradient was measured.)
- Only these colours: #FFFFFF, #F4F5F7, #0065FF, #091E42, #FAFBFC, #DEEBFF, #172B4D, #0747A6, #F0F0F0, #0052CC, #DFE1E6, #505F79, #00C7E5, #FFAB00. 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.)
- #091E42 only for text and small fills such as buttons — never as a section background or a large panel. (It covers 4% of the page.)
- #172B4D fills a few coloured bands or panels, as in the layout — a handful at most, never the page ground and never body text. (It covers 2.3% of the page, all of it in those panels.)
- 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 Charlie Text and Charlie Display; the tokens carry what stands in for them.)
- Headings and large text never heavier than weight 500. Do not make headlines bold to add emphasis. (Every size from 24px up is set at weight 500 or lighter.)
- 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, cards, split, text, statement, 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.
- No shadows other than the levels listed.
- Do not use trello.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 gradient(. There should be none.
- Every colour value in your CSS is one of the allowed colours. Nothing else, including in hover states.
- #091E42 covers about 4% of the page or less, as on the original.
- No text 24px or larger has a font-weight above 500.
- Every section, including ones the original does not have, uses only this system's colours, type, shapes and spacing.
- Content sits in a 1140px container with 190px 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.