# #331b5a

A color — cool, dark, luxury, bold, modern. Deterministic analysis from BrandSweets (no inference).

## Values

- Hex: `#331b5a`
- RGB: rgb(51, 27, 90)
- HSL: hsl(263, 54%, 23%)
- OKLCH: oklch(0.293 0.108 296.7)
- Relative luminance: 0.0223
- Nearest named color: Fabric of Space (#341758, Δ 0.953) — https://brandsweets.com/colors/fabric-of-space
- Moods: cool, dark, luxury, bold, modern
- Page: https://brandsweets.com/colors/331b5a

## Tints & shades

- Tints (toward white): #45247a, #552d95, #6736b5, #7846c8, #8f66d1, #a381d9, #baa1e3, #cebceb, #e5dcf4, #f9f7fd
- Shades (toward black): #2f1952, #2a164b, #261443, #21123b, #1f1037, #1b0e2f, #160c27, #12091f, #0d0718, #090510

## Harmonies

- Complementary: #425a1b
- Analogous: #1b225a, #531b5a
- Triadic: #5a331b, #1b5a33
- Split-complementary: #5a531b, #225a1b
- Tetradic: #5a1b22, #425a1b, #1b5a53

## Colors that go with #331b5a

Named partners (harmony on the OKLCH wheel, co-occurrence in curated palettes and brand systems, and the neutrals that carry it), best first:

- **Charcoal** #36454f [role, pool] — Charcoal is the text near-black for #331b5a: softer than #000 and cool enough to feel like part of the same palette. Seen in: Microsoft (https://brandsweets.com/colors/brands/microsoft-com), Plaid (https://brandsweets.com/colors/brands/plaid-com), CeraVe (https://brandsweets.com/colors/brands/cerave-com), Tumblr (https://brandsweets.com/colors/brands/tumblr-com). — https://brandsweets.com/colors/charcoal
- **Royal Blue** #4169e1 [harmony, pool: analogous] — Royal Blue is #331b5a's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces. Seen in: Confluent (https://brandsweets.com/colors/brands/confluent-io), Telehealth (https://brandsweets.com/palettes/modern#telehealth), Discord (https://brandsweets.com/colors/brands/discord), GEICO (https://brandsweets.com/colors/brands/geico-com). — https://brandsweets.com/colors/royalblue
- **Sea Green** #2e8b57 [harmony, pool: split] — Sea Green is a split-complement of #331b5a: nearly opposite, so it still pops against it, without the vibrating edge of a true complement. Seen in: Asana (https://brandsweets.com/colors/brands/asana-com), Subaru (https://brandsweets.com/colors/brands/subaru-com), Mushroom (https://brandsweets.com/palettes/neutral#mushroom), Wellness (https://brandsweets.com/palettes/warm#wellness). — https://brandsweets.com/colors/seagreen
- **Teal** #008080 [harmony, pool: triadic] — Teal completes a triad with #331b5a — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash. Seen in: Lufthansa (https://brandsweets.com/colors/brands/lufthansa-com), Alpine (https://brandsweets.com/palettes/cool#alpine), Sapphire & Gold (https://brandsweets.com/palettes/luxury#sapphire-and-gold), Clinic (https://brandsweets.com/palettes/clean#clinic). — https://brandsweets.com/colors/teal
- **Amber** #ffbf00 [pool] — Amber is paired with #331b5a in 5 real palettes, including Southwest Airlines's brand system and Beach Hut, as the accent. Seen in: Southwest Airlines (https://brandsweets.com/colors/brands/southwest-com), Beach Hut (https://brandsweets.com/palettes/light#beach-hut), McDonald's (https://brandsweets.com/colors/brands/mcdonalds-com), Blueprint (https://brandsweets.com/palettes/technical#blueprint). — https://brandsweets.com/colors/amber
- **Blue** #0000ff [pool] — 11 real palettes, including Sketch's brand system and Monzo's brand system put Blue beside #331b5a, as the accent. Seen in: Sketch (https://brandsweets.com/colors/brands/sketch-com), Monzo (https://brandsweets.com/colors/brands/monzo-com), Penpot (https://brandsweets.com/colors/brands/penpot-app), Readymag (https://brandsweets.com/colors/brands/readymag-com). — https://brandsweets.com/colors/blue
- **Cadet Blue** #5f9ea0 [pool] — Designers have shipped Cadet Blue with #331b5a: 7 real palettes, including SoFi's brand system and Open House, as the supporting colour. Seen in: SoFi (https://brandsweets.com/colors/brands/sofi-com), Open House (https://brandsweets.com/palettes/clean#open-house), Coastal (https://brandsweets.com/palettes/cool#coastal), Dusk (https://brandsweets.com/palettes/cool#dusk). — https://brandsweets.com/colors/cadetblue
- **Cobalt Blue** #0047ab [pool] — Designers have shipped Cobalt Blue with #331b5a: 9 real palettes, including Blue Mono and Purina Pro Plan's brand system, as the lead colour. Seen in: Blue Mono (https://brandsweets.com/palettes/cool#blue-mono), Purina Pro Plan (https://brandsweets.com/colors/brands/chewy-com), MLB (https://brandsweets.com/colors/brands/mlb-com), Fintech Trust (https://brandsweets.com/palettes/cool#fintech-trust). — https://brandsweets.com/colors/cobalt

## Contrast (WCAG 2.x, as text)

- On white (#ffffff): 14.53:1 — AA pass, AA-large pass, AAA pass
- On black (#000000): 1.45:1 — AA fail, AA-large fail, AAA fail. Fix: AA: text → #895ecf (4.57:1); AA: background → #919191 (4.61:1); AAA: text → #a989dc (7.3:1); AAA: background → #b5b5b5 (7.09:1)

## Fonts for this mood

- luxury: https://brandsweets.com/fonts/mood/luxury
- bold: https://brandsweets.com/fonts/mood/bold
- modern: https://brandsweets.com/fonts/mood/modern

## Palette tool

Open this color locked as the lead with four explored companions: https://brandsweets.com/palettes/new/331b5a-b09cc4-dfd04e-2b1f2d-e9eaf1?lock=0&style=vibrant
(Humans lock/regenerate in the tool; the URL is the state — read `lock=` back to see what they kept.)

## Connect an agent

Point any MCP client at the BrandSweets colors endpoint for the same engine:

- Endpoint: https://mcp.brandsweets.com/colors/mcp
- Tools: `analyze_color` (e.g. `analyze_color({ color: "#331b5a" })`), `check_contrast` (with fixes), `generate_palette` (explore around locks), `suggest_palette` (mood/industry → curated-first), `list_palettes`.