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
#375c81
#375c81
hex
#375c81rgb
rgb(55, 92, 129)hsl
hsl(210, 40%, 36%)oklch
oklch(0.464 0.074 249.7)Closest name: Deep Indigo (#4c567a)Relative luminance 0.1005
Colors that go with #375c81
Sienna, Amber 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.
Sienna #a0522d
complementaryshippedSienna sits directly opposite #375c81 on the wheel — the strongest contrast one hue can give another, so use it small: a button, a link colour, one highlight.
Amber #ffbf00
shippedAmber is paired with #375c81 in 5 real palettes, including McDonald's's brand system and Lemon Squeezy's brand system, as the lead colour.
Blue #0000ff
shipped6 real palettes, including Tesco's brand system and Activision's brand system put Blue beside #375c81, as the supporting colour.
Cobalt Blue #0047ab
shippedDesigners have shipped Cobalt Blue with #375c81: 6 real palettes, including Fintech Trust and Unilever's brand system, as the lead colour.
Crimson #dc143c
shippedCrimson is paired with #375c81 in 16 real palettes, including Costco's brand system and Codecademy's brand system, as the lead colour.
Firebrick #b22222
shippedDesigners have shipped Firebrick with #375c81: 5 real palettes, including Fireside and Wendy's's brand system, as the lead colour.
Goldenrod #daa520
shippedGoldenrod shows up next to #375c81 in 5 real palettes, including Open House and Mid-Century, as the accent.
White Smoke #f5f5f5
neutralWhite Smoke is the surface for #375c81: a clean near-white with no warm cast, so the cool hue stays clear instead of drifting muddy.
Real palettes that use #375c81
Tints & shades
Harmonies
Contrast
| #375c81 as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 6.98:1 | pass | pass | fail |
|
Aaon black | 3.01:1 | fail | pass | fail |
Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #375c81 as the background.
Brands using this color
Palettes built around it
Fonts for this mood
#375c81 reads as cool, modern. The font library is tagged with the same vocabulary:
mcpConnect your agent — build around #375c81
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 #375c81 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/375c81-9cabc4-df514e-1f202d-e9f1f1?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