Color

#666cb7

#666cb7
hex#666cb7
rgbrgb(102, 108, 183)
hslhsl(236, 36%, 56%)
oklchoklch(0.56 0.116 278.5)
Closest name: Loch Ness (#5f6db0)Relative luminance 0.1697

Colors that go with #666cb7

Charcoal, Sea Green and Amber lead the list. Each partner is a real named colour with the reason it works — a wheel relationship, a neutral that carries it, or a pairing lifted from a palette or brand system that actually shipped — and every pair opens in the palette tool.

Tints & shades

Every swatch is its own page — click any to analyze it.

Harmonies

Complementary

Open in tool →

#b7b266

#6694b7 · #8966b7

#b7666c · #6cb766

Split-complementary

Open in tool →

#b78966 · #94b766

#b76694 · #b7b266 · #66b789

Contrast

#666cb7 as textRatioAAAA largeAAAFix
Aaon white
4.78:1passpassfail
  • AAA: use #4b51a0 as the text (7.04:1)
Aaon black
4.39:1failpassfail
  • AA: use #6a6fb9 as the text (4.59:1)
  • AAA: use #8d91c9 as the text (7.03:1)
  • AA: or shift the background to #fafafa (4.58:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #666cb7 as the background.

Brands using this color

Fonts for this mood

#666cb7 reads as cool, modern. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #666cb7
live endpoint

Point any MCP client at the shared colors endpoint and your agent gets the same engine as this page — direct_palette, edit_direction, check_palette, check_contrast — read-only, no key. Every direction it proposes comes with a /colors/d/… link: open it, lock what you like, paste the link back, and the agent edits rather than re-rolls.

endpointhttps://mcp.brandsweets.com/colors/mcp
claude mcp add --transport http brandsweets-colors https://mcp.brandsweets.com/colors/mcp
try this prompt

analyze #666cb7 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/666cb7-9e9cc4-df8f4e-241f2d-e9eef1?lock=0&style=vibrant

Want the agent to remember your picks and write them into a living brand? Create a free BrandSweets workspace.

Machine-readable: color.md