# #421b5a

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

## Values

- Hex: `#421b5a`
- RGB: rgb(66, 27, 90)
- HSL: hsl(277, 54%, 23%)
- OKLCH: oklch(0.313 0.111 309.9)
- Relative luminance: 0.0268
- Nearest named color: Fading Horizon (#442266, Δ 2.582) — https://brandsweets.com/colors/fading-horizon
- Moods: cool, dark, luxury, bold, modern
- Page: https://brandsweets.com/colors/421b5a

## Tints & shades

- Tints (toward white): #59247a, #6d2d95, #8436b5, #9646c8, #a866d1, #b881d9, #caa1e3, #d9bceb, #ebdcf4, #fbf7fd
- Shades (toward black): #3c1952, #37164b, #311443, #2b123b, #281037, #220e2f, #1d0c27, #17091f, #110718, #0b0510

## Harmonies

- Complementary: #335a1b
- Analogous: #221b5a, #5a1b53
- Triadic: #5a421b, #1b5a42
- Split-complementary: #535a1b, #1b5a22
- Tetradic: #5a221b, #335a1b, #1b535a

## Colors that go with #421b5a

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 #421b5a: softer than #000 and cool enough to feel like part of the same palette. Seen in: Hinge (https://brandsweets.com/colors/brands/hinge-co), Microsoft (https://brandsweets.com/colors/brands/microsoft-com), Plaid (https://brandsweets.com/colors/brands/plaid-com), Tumblr (https://brandsweets.com/colors/brands/tumblr-com). — https://brandsweets.com/colors/charcoal
- **Sea Green** #2e8b57 [harmony, pool: complementary] — Sea Green sits directly opposite #421b5a on the wheel — the strongest contrast one hue can give another, so use it small: a button, a link colour, one highlight. 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). — https://brandsweets.com/colors/seagreen
- **Blue** #0000ff [pool] — 7 real palettes, including Sketch's brand system and Monzo's brand system put Blue beside #421b5a, as the accent. Seen in: Sketch (https://brandsweets.com/colors/brands/sketch-com), Monzo (https://brandsweets.com/colors/brands/monzo-com), Tim Hortons (https://brandsweets.com/colors/brands/timhortons-com), Minecraft (https://brandsweets.com/colors/brands/minecraft-net). — https://brandsweets.com/colors/blue
- **Cadet Blue** #5f9ea0 [pool] — Designers have shipped Cadet Blue with #421b5a: 5 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 #421b5a: 4 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
- **Crimson** #dc143c [pool] — Crimson is paired with #421b5a in 9 real palettes, including Marvel's brand system and Casper Sleep's brand system, as the accent. Seen in: Marvel (https://brandsweets.com/colors/brands/marvel-com), Casper Sleep (https://brandsweets.com/colors/brands/casper-com), Frost & Ember (https://brandsweets.com/palettes/bold#frost-and-ember), Nintendo (https://brandsweets.com/colors/brands/nintendo-com). — https://brandsweets.com/colors/crimson
- **Denim** #1560bd [pool] — Designers have shipped Denim with #421b5a: 16 real palettes, including Discover's brand system and Hinge's brand system, as the supporting colour. Seen in: Discover (https://brandsweets.com/colors/brands/discover-com), Hinge (https://brandsweets.com/colors/brands/hinge-co), Panasonic (https://brandsweets.com/colors/brands/panasonic-com), Open House (https://brandsweets.com/palettes/clean#open-house). — https://brandsweets.com/colors/denim
- **Firebrick** #b22222 [pool] — Designers have shipped Firebrick with #421b5a: 7 real palettes, including Nintendo's brand system and Fenty Beauty's brand system, as the accent. Seen in: Nintendo (https://brandsweets.com/colors/brands/nintendo-com), Fenty Beauty (https://brandsweets.com/colors/brands/fentybeauty-com), Vodafone (https://brandsweets.com/colors/brands/vodafone-com), MLB (https://brandsweets.com/colors/brands/mlb-com). — https://brandsweets.com/colors/firebrick

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

- On white (#ffffff): 13.67:1 — AA pass, AA-large pass, AAA pass
- On black (#000000): 1.54:1 — AA fail, AA-large fail, AAA fail. Fix: AA: text → #9d52cb (4.5:1); AA: background → #949494 (4.51:1); AAA: text → #b881d9 (7.18:1); AAA: background → #bababa (7.04:1)

## 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/421b5a-b99cc4-bdcb62-2d1f2c-eae9f1?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: "#421b5a" })`), `check_contrast` (with fixes), `generate_palette` (explore around locks), `suggest_palette` (mood/industry → curated-first), `list_palettes`.