Color
#3f188b
#3f188brgb(63, 24, 139)hsl(260, 71%, 32%)oklch(0.35 0.172 289.7)Colors that go with #3f188b
Royal Blue, Crimson and Denim 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.
Royal Blue #4169e1
analogousshippedRoyal Blue is #3f188b's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces.
Crimson #dc143c
shippedCrimson is paired with #3f188b in 6 real palettes, including Casper Sleep's brand system and Pepsi's brand system, as the lead colour.
Denim #1560bd
shippedDesigners have shipped Denim with #3f188b: 5 real palettes, including Bank of America's brand system and Warbyparker's brand system, as the accent.
Steel Blue #4682b4
shippedDesigners have shipped Steel Blue with #3f188b: 5 real palettes, including FedEx's brand system and Hershey's's brand system, as the accent.
Olive Green #808000
complementaryOlive Green sits directly opposite #3f188b on the wheel — the strongest contrast one hue can give another, so use it small: a button, a link colour, one highlight.
Charcoal #36454f
neutralshippedCharcoal is the text near-black for #3f188b: softer than #000 and cool enough to feel like part of the same palette.
Red #ff0000
shippedRed is paired with #3f188b in 3 real palettes, including Twitch's brand system and Walgreens's brand system, as the accent.
Taupe #483c32
shippedTaupe is paired with #3f188b in 3 real palettes, including Gillette's brand system and Datadog's brand system, as the lead colour.
Real palettes that use #3f188b
Tints & shades
Harmonies
Contrast
| #3f188b as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 12.25:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 1.71:1 | 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 #3f188b as the background.
Brands using this color
No public brand in the corpus uses this exact color yet. Extract a brand to add one.
Fonts for this mood
#3f188b reads as cool, vivid, technical. The font library is tagged with the same vocabulary:
Point 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.
https://mcp.brandsweets.com/colors/mcpclaude mcp add --transport http brandsweets-colors https://mcp.brandsweets.com/colors/mcp
›analyze #3f188b and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
/palettes/new/3f188b-ae9cc4-dfc94e-2a1f2d-e9ebf1?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