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
#3f5683
#3f5683
hex
#3f5683rgb
rgb(63, 86, 131)hsl
hsl(220, 35%, 38%)oklch
oklch(0.455 0.079 263)Closest name: Dusk (#4e5481)Relative luminance 0.0935
Colors that go with #3f5683
Sea Green, Steel Blue and Sienna 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 #3f5683 — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash.
Steel Blue #4682b4
analogousshippedSteel Blue is #3f5683's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces.
Sienna #a0522d
complementaryshippedSienna sits directly opposite #3f5683 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 #3f5683 in 4 real palettes, including McDonald's's brand system and Warner Bros.'s brand system, as the lead colour.
Blue #0000ff
shipped6 real palettes, including Tesco's brand system and CVS's brand system put Blue beside #3f5683, as the supporting colour.
Crimson #dc143c
shippedCrimson is paired with #3f5683 in 14 real palettes, including Walgreens's brand system and Costco's brand system, as the lead colour.
Firebrick #b22222
shippedDesigners have shipped Firebrick with #3f5683: 6 real palettes, including Campbell's's brand system and Fireside, as the supporting colour.
White Smoke #f5f5f5
neutralWhite Smoke is the surface for #3f5683: a clean near-white with no warm cast, so the cool hue stays clear instead of drifting muddy.
Real palettes that use #3f5683
Tints & shades
Harmonies
Contrast
| #3f5683 as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 7.32:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 2.87:1 | 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 #3f5683 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
Fonts for this mood
#3f5683 reads as cool, modern. The font library is tagged with the same vocabulary:
mcpConnect your agent — build around #3f5683
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 #3f5683 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/3f5683-9ca5c4-df694e-211f2d-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