# #3f537d

A color — cool, muted. Deterministic analysis from BrandSweets (no inference).

## Values

- Hex: `#3f537d`
- RGB: rgb(63, 83, 125)
- HSL: hsl(221, 33%, 37%)
- OKLCH: oklch(0.445 0.074 264.2)
- Relative luminance: 0.0872
- Nearest named color: Deep Indigo (#4c567a, Δ 2.203) — https://brandsweets.com/colors/deep-indigo
- Moods: cool, muted
- Page: https://brandsweets.com/colors/3f537d

## Tints & shades

- Tints (toward white): #496092, #546ea6, #667eb2, #7b90bc, #92a4c8, #a7b5d3, #bbc6dd, #d0d7e7, #e4e8f1, #f8f9fc
- Shades (toward black): #3a4c73, #334366, #2e3d5c, #293651, #242f47, #1d263a, #181f2f, #131925, #0c1018, #07090e

## Harmonies

- Complementary: #7d6a3f
- Analogous: #3f727d, #4b3f7d
- Triadic: #7d3f53, #537d3f
- Split-complementary: #7d4b3f, #727d3f
- Tetradic: #7d3f72, #7d6a3f, #3f7d4b

## Colors that go with #3f537d

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

- **Sea Green** #2e8b57 [harmony, pool: triadic] — Sea Green completes a triad with #3f537d — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash. Seen in: Jack Daniel's (https://brandsweets.com/colors/brands/jackdaniels-com), Subaru (https://brandsweets.com/colors/brands/subaru-com), Netflix (https://brandsweets.com/colors/brands/netflix), Paramount+ (https://brandsweets.com/colors/brands/paramountplus-com). — https://brandsweets.com/colors/seagreen
- **Steel Blue** #4682b4 [harmony, pool: analogous] — Steel Blue is #3f537d's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces. Seen in: Capital One (https://brandsweets.com/colors/brands/capitalone-com), Auth0 (https://brandsweets.com/colors/brands/auth0-com), American Express (https://brandsweets.com/colors/brands/americanexpress-com), Glacier (https://brandsweets.com/palettes/cool#glacier). — https://brandsweets.com/colors/steelblue
- **Blue** #0000ff [pool] — 7 real palettes, including Tesco's brand system and CVS's brand system put Blue beside #3f537d, as the supporting colour. Seen in: Tesco (https://brandsweets.com/colors/brands/tesco-com), CVS (https://brandsweets.com/colors/brands/cvs-com), Alaska Airlines (https://brandsweets.com/colors/brands/alaskaair-com), Activision (https://brandsweets.com/colors/brands/activision-com). — https://brandsweets.com/colors/blue
- **Cornflower Blue** #6495ed [pool] — Designers have shipped Cornflower Blue with #3f537d: 4 real palettes, including Coca-Cola's brand system and Blizzard's brand system, as the supporting colour. Seen in: Coca-Cola (https://brandsweets.com/colors/brands/coca-cola-com), Blizzard (https://brandsweets.com/colors/brands/blizzard-com), Blue Mono (https://brandsweets.com/palettes/cool#blue-mono), Gopro (https://brandsweets.com/colors/brands/gopro-com). — https://brandsweets.com/colors/cornflowerblue
- **Crimson** #dc143c [pool] — Crimson is paired with #3f537d in 15 real palettes, including Codecademy's brand system and Walgreens's brand system, as the accent. Seen in: Codecademy (https://brandsweets.com/colors/brands/codecademy-com), Walgreens (https://brandsweets.com/colors/brands/walgreens-com), Wells Fargo (https://brandsweets.com/colors/brands/wellsfargo-com), Costco (https://brandsweets.com/colors/brands/costco-com). — https://brandsweets.com/colors/crimson
- **Denim** #1560bd [pool] — Designers have shipped Denim with #3f537d: 16 real palettes, including HP's brand system and Dutch Bros's brand system, as the accent. Seen in: HP (https://brandsweets.com/colors/brands/hp-com), Dutch Bros (https://brandsweets.com/colors/brands/dutchbros-com), The New York Times (https://brandsweets.com/colors/brands/nytimes-com), Unilever (https://brandsweets.com/colors/brands/unilever-com). — https://brandsweets.com/colors/denim
- **Firebrick** #b22222 [pool] — Designers have shipped Firebrick with #3f537d: 4 real palettes, including Fireside and Campbell's's brand system, as the lead colour. Seen in: Fireside (https://brandsweets.com/palettes/dark#fireside), Campbell's (https://brandsweets.com/colors/brands/campbells-com), Wendy's (https://brandsweets.com/colors/brands/wendys-com), AT&T (https://brandsweets.com/colors/brands/att-com). — https://brandsweets.com/colors/firebrick
- **White Smoke** #f5f5f5 [role] — White Smoke is the surface for #3f537d: a clean near-white with no warm cast, so the cool hue stays clear instead of drifting muddy. — https://brandsweets.com/colors/whitesmoke

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

- On white (#ffffff): 7.65:1 — AA pass, AA-large pass, AAA pass
- On black (#000000): 2.74:1 — AA fail, AA-large fail, AAA fail. Fix: AA: text → #5c76ad (4.65:1); AA: background → #c7c7c7 (4.53:1); AAA: text → #8295c0 (7.01:1); AAA: background → #f5f5f5 (7.02:1)

## Palette tool

Open this color locked as the lead with four explored companions: https://brandsweets.com/palettes/new/3f537d-9ca4c4-df6b4e-211f2d-e9eff1?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: "#3f537d" })`), `check_contrast` (with fixes), `generate_palette` (explore around locks), `suggest_palette` (mood/industry → curated-first), `list_palettes`.