Dusk
Open in tool →Slate blue with a copper accent — calm, professional, slightly editorial; suits consultancies and journals.
Color
#3f5c8d
#3f5c8d
hex
#3f5c8drgb
rgb(63, 92, 141)hsl
hsl(218, 38%, 40%)oklch
oklch(0.475 0.087 260.4)Closest name: Dusk (#4e5481)Relative luminance 0.1063
Colors that go with #3f5c8d
Charcoal, Sea Green 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.
Charcoal #36454f
neutralshippedCharcoal is the text near-black for #3f5c8d: softer than #000 and cool enough to feel like part of the same palette.
Sea Green #2e8b57
triadicshippedSea Green completes a triad with #3f5c8d — 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 #3f5c8d 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 #3f5c8d in 6 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 Activision's brand system put Blue beside #3f5c8d, as the supporting colour.
Cornflower Blue #6495ed
shippedDesigners have shipped Cornflower Blue with #3f5c8d: 4 real palettes, including Coca-Cola's brand system and Gopro's brand system, as the supporting colour.
Crimson #dc143c
shippedCrimson is paired with #3f5c8d in 18 real palettes, including Costco's brand system and Walgreens's brand system, as the lead colour.
Deep Sky Blue #00bfff
shippedDesigners have shipped Deep Sky Blue with #3f5c8d: 4 real palettes, including Venmo's brand system and Deep Water, as the supporting colour.
Real palettes that use #3f5c8d
Tints & shades
Harmonies
Contrast
| #3f5c8d as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 6.72:1 | pass | pass | fail |
|
Aaon black | 3.13:1 | 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 #3f5c8d 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
#3f5c8d reads as cool, modern. The font library is tagged with the same vocabulary:
mcpConnect your agent — build around #3f5c8d
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 #3f5c8d and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/3f5c8d-9ca6c4-df644e-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