# #666da3

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

## Values

- Hex: `#666da3`
- RGB: rgb(102, 109, 163)
- HSL: hsl(233, 25%, 52%)
- OKLCH: oklch(0.552 0.084 277.6)
- Relative luminance: 0.1641
- Nearest named color: Loch Ness (#5f6db0, Δ 2.228) — https://brandsweets.com/colors/loch-ness
- Moods: cool, muted
- Page: https://brandsweets.com/colors/666da3

## Tints & shades

- Tints (toward white): #767cad, #8388b4, #9398be, #9fa4c6, #afb3cf, #bfc2d9, #cccee0, #dcdeea, #e9eaf2, #f9f9fb
- Shades (toward black): #5a6196, #505786, #494e79, #3f4469, #363a59, #2c2f49, #222539, #1b1d2d, #11131d, #08080d

## Harmonies

- Complementary: #a39c66
- Analogous: #668ca3, #7d66a3
- Triadic: #a3666d, #6da366
- Split-complementary: #a37d66, #8ca366
- Tetradic: #a3668c, #a39c66, #66a37d

## Colors that go with #666da3

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 #666da3: softer than #000 and cool enough to feel like part of the same palette. Seen in: Campus (https://brandsweets.com/palettes/friendly#campus), Plaid (https://brandsweets.com/colors/brands/plaid-com), Bloomberg (https://brandsweets.com/colors/brands/bloomberg-com), Hermès (https://brandsweets.com/colors/brands/hermes-com). — https://brandsweets.com/colors/charcoal
- **Sea Green** #2e8b57 [harmony, pool: triadic] — Sea Green completes a triad with #666da3 — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash. Seen in: Lemon Squeezy (https://brandsweets.com/colors/brands/lemonsqueezy-com), Jack Daniel's (https://brandsweets.com/colors/brands/jackdaniels-com), Netflix (https://brandsweets.com/colors/brands/netflix), Paramount+ (https://brandsweets.com/colors/brands/paramountplus-com). — https://brandsweets.com/colors/seagreen
- **Amber** #ffbf00 [pool] — Amber is paired with #666da3 in 8 real palettes, including Lemon Squeezy's brand system and Wired's brand system, as the lead colour. Seen in: Lemon Squeezy (https://brandsweets.com/colors/brands/lemonsqueezy-com), Wired (https://brandsweets.com/colors/brands/wired-com), Beach Hut (https://brandsweets.com/palettes/light#beach-hut), McDonald's (https://brandsweets.com/colors/brands/mcdonalds-com). — https://brandsweets.com/colors/amber
- **Cobalt Blue** #0047ab [pool] — Designers have shipped Cobalt Blue with #666da3: 7 real palettes, including Fintech Trust and Glacier, as the lead colour. Seen in: Fintech Trust (https://brandsweets.com/palettes/cool#fintech-trust), Glacier (https://brandsweets.com/palettes/cool#glacier), Hershey's (https://brandsweets.com/colors/brands/hersheys-com), General Mills (https://brandsweets.com/colors/brands/generalmills-com). — https://brandsweets.com/colors/cobalt
- **Copper** #b87333 [pool] — Designers have shipped Copper with #666da3: 4 real palettes, including Dusk and Riverbed, as the accent. Seen in: Dusk (https://brandsweets.com/palettes/cool#dusk), Riverbed (https://brandsweets.com/palettes/muted#riverbed), Notion (https://brandsweets.com/colors/brands/notion), Atelier (https://brandsweets.com/palettes/elegant#atelier). — https://brandsweets.com/colors/copper
- **Crimson** #dc143c [pool] — Crimson is paired with #666da3 in 15 real palettes, including Marvel's brand system and Retro Pop, as the accent. Seen in: Marvel (https://brandsweets.com/colors/brands/marvel-com), Retro Pop (https://brandsweets.com/palettes/playful#retro-pop), Wendy's (https://brandsweets.com/colors/brands/wendys-com), State Farm (https://brandsweets.com/colors/brands/statefarm-com). — https://brandsweets.com/colors/crimson
- **Deep Sky Blue** #00bfff [pool] — Designers have shipped Deep Sky Blue with #666da3: 5 real palettes, including Astro's brand system and Deep Water, as the supporting colour. Seen in: Astro (https://brandsweets.com/colors/brands/astro-build), Deep Water (https://brandsweets.com/palettes/dark#deep-water), Venmo (https://brandsweets.com/colors/brands/venmo-com), Telegram (https://brandsweets.com/colors/brands/telegram-org). — https://brandsweets.com/colors/deepskyblue
- **Denim** #1560bd [pool] — Designers have shipped Denim with #666da3: 14 real palettes, including Campus and The New York Times's brand system, as the lead colour. Seen in: Campus (https://brandsweets.com/palettes/friendly#campus), The New York Times (https://brandsweets.com/colors/brands/nytimes-com), Discover (https://brandsweets.com/colors/brands/discover-com), American Express (https://brandsweets.com/colors/brands/americanexpress-com). — https://brandsweets.com/colors/denim

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

- On white (#ffffff): 4.91:1 — AA pass, AA-large pass, AAA fail. Fix: AAA: text → #4e5583 (7.12:1)
- On black (#000000): 4.28:1 — AA fail, AA-large pass, AAA fail. Fix: AA: text → #6c73a7 (4.65:1); AA: background → #f7f7f7 (4.58:1); AAA: text → #8f95bc (7.19:1)

## Palette tool

Open this color locked as the lead with four explored companions: https://brandsweets.com/palettes/new/666da3-9c9cc4-df884e-241f2d-e9eef1?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: "#666da3" })`), `check_contrast` (with fixes), `generate_palette` (explore around locks), `suggest_palette` (mood/industry → curated-first), `list_palettes`.