Harbour
Open in tool →Steel blue and haze with a buoy orange on a pale grey — the maritime palette every port town uses for a reason.
Color
#42587b
#42587b
hex
#42587brgb
rgb(66, 88, 123)hsl
hsl(217, 30%, 37%)oklch
oklch(0.458 0.064 259.5)Closest name: Deep Indigo (#4c567a)Relative luminance 0.0957
Colors that go with #42587b
Sea Green, Sienna and Blue 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.
Sea Green #2e8b57
triadicshippedSea Green completes a triad with #42587b — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash.
Sienna #a0522d
complementaryshippedSienna sits directly opposite #42587b on the wheel — the strongest contrast one hue can give another, so use it small: a button, a link colour, one highlight.
Blue #0000ff
shipped6 real palettes, including Tesco's brand system and CVS's brand system put Blue beside #42587b, as the supporting colour.
Cadet Blue #5f9ea0
shippedDesigners have shipped Cadet Blue with #42587b: 4 real palettes, including Dusk and Open House, as the supporting colour.
Crimson #dc143c
shippedCrimson is paired with #42587b in 13 real palettes, including Codecademy's brand system and Walgreens's brand system, as the accent.
Denim #1560bd
shippedDesigners have shipped Denim with #42587b: 16 real palettes, including HP's brand system and The New York Times's brand system, as the accent.
Firebrick #b22222
shippedDesigners have shipped Firebrick with #42587b: 4 real palettes, including Fireside and Wendy's's brand system, as the lead colour.
White Smoke #f5f5f5
neutralWhite Smoke is the surface for #42587b: a clean near-white with no warm cast, so the cool hue stays clear instead of drifting muddy.
Real palettes that use #42587b
Tints & shades
Harmonies
Contrast
| #42587b as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 7.21:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 2.91:1 | fail | fail | fail |
Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #42587b as the background.
Brands using this color
Palettes built around it
mcpConnect your agent — build around #42587b
live endpointPoint 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.
endpoint
https://mcp.brandsweets.com/colors/mcpclaude mcp add --transport http brandsweets-colors https://mcp.brandsweets.com/colors/mcp
try this prompt
›analyze #42587b and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/42587b-9ca7c4-df624e-201f2d-e9f0f1?lock=0&style=vibrantWant the agent to remember your picks and write them into a living brand? Create a free BrandSweets workspace.
Machine-readable: color.md