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
#3f5f7d
#3f5f7d
hex
#3f5f7drgb
rgb(63, 95, 125)hsl
hsl(209, 33%, 37%)oklch
oklch(0.474 0.062 247.7)Closest name: Atlantis (#336172)Relative luminance 0.1072
Colors that go with #3f5f7d
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 #3f5f7d 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 #3f5f7d 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 Activision's brand system and Tesco's brand system put Blue beside #3f5f7d, as the accent.
Cobalt Blue #0047ab
shippedDesigners have shipped Cobalt Blue with #3f5f7d: 6 real palettes, including Fintech Trust and Ink & Paper, as the lead colour.
Copper #b87333
shippedDesigners have shipped Copper with #3f5f7d: 4 real palettes, including Dusk and Desert Road, as the accent.
Crimson #dc143c
shippedCrimson is paired with #3f5f7d in 16 real palettes, including Codecademy's brand system and McDonald's's brand system, as the accent.
Deep Sky Blue #00bfff
shippedDesigners have shipped Deep Sky Blue with #3f5f7d: 4 real palettes, including Lamborghini's brand system and Venmo's brand system, as the supporting colour.
White Smoke #f5f5f5
neutralWhite Smoke is the surface for #3f5f7d: a clean near-white with no warm cast, so the cool hue stays clear instead of drifting muddy.
Real palettes that use #3f5f7d
Tints & shades
Harmonies
Contrast
| #3f5f7d as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 6.68:1 | pass | pass | fail |
|
Aaon black | 3.14:1 | 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 #3f5f7d as the background.
Brands using this color
No public brand in the corpus uses this exact color yet. Extract a brand to add one.
Palettes built around it
mcpConnect your agent — build around #3f5f7d
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 #3f5f7d and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/3f5f7d-9cacc4-df4e4e-1f212d-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