Color System

Color System

Overview

A curated library of ready-to-use color palettes (light + dark) across four domains — web-app UI, marketing/landing, data visualization, and terminal/TUI — plus the methodology to build new palettes and verify their accessibility.

Core principle: choose colors by semantic role (background, text, primary, error…), not by raw hue. Every palette here maps hexes to roles, so a theme stays swappable, consistent, and accessible. Pick a role first, then read its hex — hardcoding a hex where a role belongs is what breaks theming later.

Navigation

The index and role contract below answer "which palette" on their own. Load one reference file when the task needs its payload — not all four.

Palette Library (quick index)

Where one palette is the right first reach it is marked ⭐; marketing and TUI have no default because the choice follows the brand or the user's own terminal theme.

Web App UI — light + dark, 13 semantic roles + a triad per color

• Carbon ⭐ (default) — deep slate-blue, dark-first. Analytics dashboards, perf reports & dev tooling. Ships a full dashboard kit (A–F grade pills, ordered stage sequence, inline-code tone, success highlight). Reach for Graphite instead when light mode must be hand-tuned-equal.
• Graphite — cool slate + blue. Dense B2B dashboards, dev tools; the light+dark parity default.
• Evergreen — emerald brand on true-neutral zinc. Fresh, confident, non-blue identity.
• Terracotta — warm clay/espresso neutrals + rust. Editorial, content platforms, writing tools.
• Bloom — pastel periwinkle/violet, deep dark mode. Friendly dev tools, playful-but-clean apps.
• Teal Slate — deep teal on cool slate, single warm accent. Technical reports, SRE / rate-limit dashboards; pairs with a mono face for figures.

Generated from 12-step OKLCH scales, which ship alongside their roles so they can be extended or re-derived:

• Dusk — indigo primary, turquoise accent, near-neutral cool greys. Focus tools, editors, long-session apps.
• Driftwood — deep marine primary on warm sand neutrals, clay accent. The one that swings its neutrals cool in dark mode.
• Meadow — muted sage primary, old-gold accent, warm bone neutrals. The softest of the set; restful rather than confident.

Marketing / Landing — light + dark, hero gradients

• Sunbloom — refined coral/amber warmth. Approachable consumer/creator brands.
• Tidewater — teal/sage. Fintech, wellness, B2B trust.
• Obsidian & Gold — near-black + metallic gold. Premium, luxury, agency.
• Paper & Ink — warm paper + ink black + one terracotta accent. Blogs, long-form, portfolios.

Data Viz — colorblind-aware, warm/cool earthy

• Categorical: Lunar Valley ⭐ (default) · Hearthstead · Vintage Warm · Glass Wall · Okabe-Ito (use when CVD-safety is a hard requirement)
• Sequential: Viridis ⭐ (default) · Magma · Inferno · Plasma · ColorBrewer Blues · YlOrRd (all perceptually uniform)
• Diverging: Console & Window ⭐ (default) · Alien Sun · Orchard Dusk · Coffee & Coolant — all warm↔cool, no red↔green

Terminal / TUI — 16-ANSI + bg/fg/cursor/selection

• Solarized Dark · Nord · Catppuccin Mocha · Catppuccin Latte (the one light scheme) · Dracula · Tokyo Night

→ Full hex tables for every palette: references/palettes.md

Semantic roles (the contract)

UI palettes fill these roles. Map intent to a role, then the role to a hex.

Each colored role then needs a triad, because one hex cannot do three jobs. A value authored to be sat on is not automatically legible as text, and a solid fill is far too loud as a badge background at table density.

Ready-made triads for all nine UI palettes are in palettes.md. Dark-mode fills are light hues, so their labels are the palette's darkest neutral, not white.

Data-viz palettes instead provide ordered color lists (categorical = distinct series; sequential = low→high ramp; diverging = warm↔cool with a neutral midpoint). TUI schemes provide the 16 ANSI slots plus 4 special roles.

Core Concepts

• Design in OKLCH, not HSL. OKLCH is perceptually uniform; HSL "lightness" lies (equal-L blue looks far darker than equal-L yellow), so even HSL steps produce lumpy scales.
• Harmony: pick a scheme (monochromatic / analogous / complementary / triadic…) and let one color dominate in saturation and area; desaturate the rest.
• Scales: 10–12 steps, step lightness evenly, peak chroma in the mid-range and taper it at the extremes so tints aren't washed out and shades aren't muddy.
• Contrast: WCAG AA — body text ≥ 4.5:1, large text & UI/borders ≥ 3:1.
• Light vs dark is not an inversion, and WCAG 2 ratios overstate contrast near black. Both failure modes and their fixes are in Gotchas below; thresholds and the APCA procedure are in references/contrast.md.
• Colorblind-safety: encode meaning with text, icon, or position in addition to hue, since ~8% of men can't separate the hues alone. For diverging data use warm↔cool (blue/orange, teal/rose) rather than red↔green.

Examples

Example: choosing colors for a SaaS dashboard

✅ Desired

User: "I need colors for an admin dashboard, light and dark."
→ Recommend Carbon (deep slate-blue, dark-first, made for dense data UI) — the default;
  offer Graphite if hand-tuned light-mode parity matters more than the dashboard kit.
→ Copy its role→hex table from palettes.md (both modes).
→ Apply by role: background→surface→border→text, primary for the main CTA,
  success/warning/error for status badges. Confirm text-primary on background ≥ 4.5:1.

❌ Anti-pattern

→ Pick four hues from a Coolors palette and assign them ad hoc: #2b2d42 nav, #8d99ae text,
  #edf2f4 background, #ef233c buttons. Dark mode = invert the hexes.

Why it works: a role-mapped palette drops straight into CSS variables and is accessible by construction. The ad-hoc version has no neutral ramp, no elevation tiers, no status colors, and inverting a light palette produces pure-black surfaces and washed-out brand hues (see Gotchas: light vs dark is not an inversion).

Example: status badge color

✅ Desired

.badge-error { background: var(--error); color: #fff; }   /* role, not a hardcoded red */

❌ Anti-pattern

.badge-error { background: #ff0000; color: #000; }   /* raw hue; #f00 on #000 ≈ 5.2:1 but glares,
                                                         and won't theme or switch to dark mode */

Why it fails: hardcoding a hue breaks theming and dark mode, and pure-red/pure-black causes halation.

Example: picking a chart palette

✅ Desired

Categorical series (≤8) → Lunar Valley (default), or Okabe-Ito when CVD-safety is required.
Continuous low→high → Viridis (perceptually uniform, colorblind-safe).
Signed data with a midpoint → Console & Window (warm↔cool, neutral center).
Past ~8 categorical colors, series stop being distinguishable — aggregate into "Other" instead.

❌ Anti-pattern

Twelve categorical series colored from the UI palette's success/warning/error/info roles plus
brand tints; profit/loss encoded green↔red with no labels.

Why it works: matches the data's structure to the right palette family and respects the distinguishability limit. The anti-pattern reuses UI status roles that collide with series identity, exceeds the ~8-hue limit, and encodes red↔green with no text or icon backup for colorblind viewers.

Gotchas

• Symptom: Brand color is unreadable as body text. Cause: Saturated mid-tones (amber, coral, teal) often fail 4.5:1 on their own background — a fill color and a text color are different steps of the same ramp. Fix: keep fill and link as separate values; step the text one darker until it clears. In this library only Evergreen light diverges (#059669 carries a button label at 4.70:1 but reaches 3.77:1 as a link on white, so its link is #00875b), which is exactly why the split gets missed.
• Symptom: Status badges look correct but shout at table density. Cause: a solid --error fill behind white text is right for a button and far too loud for a row-level badge. Fix: use the {c}-subtle background with its paired {c}-emphasis label. Reusing the status hue as its own label on that tint misses 4.5:1 more often than not — take the paired value from palettes.md rather than assuming.
• Symptom: A palette generated from a 12-step scale still fails contrast. Cause: the step map is not a contrast guarantee. Radix guarantees steps 11 and 12 against step 2 and nothing else; step 9 rarely carries a 4.5:1 button label, and step 8 rarely reaches 3:1 as a control edge. Fix: solve those two against their actual ground. In light mode commit to a white label and step the fill darker — solving toward whichever label already scores higher produces a pale wash that passes and looks weak.
• Symptom: A palette that looks right in light mode feels muddy in dark. Cause: the neutral tint was chosen once and inherited. A warm hue that reads as paper at high lightness reads as brown at low lightness. Fix: re-decide neutral hue and chroma per mode; swinging cool at very low chroma is the usual answer. Driftwood in palettes.md does this (hue 64 light, 224 dark); Meadow's sage did not need it.
• Symptom: A palette copied from Color Hunt, Coolors or a trend article cannot build an interface. Cause: gallery palettes are four decorative hues with no neutral ramp, no dark ink and no states — 16 of the 30 most-liked Color Hunt palettes cannot carry 4.5:1 body text with any pair of their colors. Fix: take the hues as seed material and build scales from them (build-your-own.md); Dusk, Driftwood and Meadow were made this way.
• Symptom: Secondary/muted text ("dimmed", text-secondary) looks fine in the design tool but fails contrast in the app. Cause: component libraries ship a default muted-text color (e.g. Mantine's dimmed) tuned for visual hierarchy, not contrast — commonly landing around ~3.4:1, well under the 4.5:1 AA floor. Fix: pick and verify your own text-secondary hex against contrast.md instead of inheriting the library default, and re-check per theme — the same override can pass in one theme and fail in another. Re-verify on tinted/elevated surfaces (cards, striped rows) too, not just the flat canvas.
• Symptom: Dark mode "passes WCAG" but is hard to read. Cause: WCAG 2 math overstates contrast near black. Fix: re-check dark pairs with APCA (Lc), not the 4.5:1 ratio alone.
• Symptom: Dark theme looks flat, elevation unreadable. Cause: pure #000 background + same-lightness surfaces. Fix: raise the base to ~`#0d1117–#1e1e2e` and make each elevation tier lighter.
• Symptom: A chart is unreadable for colorblind viewers. Cause: red↔green encoding or hue-only meaning. Fix: switch to a warm↔cool diverging palette and add labels/icons; for categorical use the Okabe-Ito safe set (in palettes.md).
• Symptom: Chart text stays low-contrast even though your palette defines the right text color. Cause: charting libraries (Recharts, Mantine charts) render axis/legend/value text as SVG with their own inline fill, bypassing your color tokens entirely. Fix: target the library's text elements directly (e.g. .recharts-wrapper text { fill: var(--text) }) — the CSS cascade never reaches it.
• Symptom: TUI colors vanish on some terminals. Cause: hardcoded hex, or load-bearing text placed in bright-black (slot 8). Fix: bind meaning to ANSI slots 1–6 so the user's own theme renders it, and keep slot 8 for de-emphasis only.
• Symptom: Palette steps look lumpy/uneven. Cause: stepping lightness in HSL/RGB. Fix: rebuild the scale in OKLCH; see build-your-own.md.

Integration

• frontend-design — builds the components and layout; this skill supplies the color decisions. Pick a palette here, implement the UI there.
• typography — owns size, weight, and line-height; the two share only the contrast floor. When text is unreadable, decide first whether the defect is the color pair (here) or the size/weight (typography).
• dataviz — owns chart form, axes, and encoding. Take the categorical/sequential/diverging palette from here and hand it to that skill as the series colors.