Color
#3f5178
#3f5178rgb(63, 81, 120)hsl(221, 31%, 36%)oklch(0.438 0.069 264.8)Colors that go with #3f5178
Sea Green, Steel Blue 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.
Sea Green #2e8b57
triadicshippedSea Green completes a triad with #3f5178 — 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 #3f5178's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces.
Blue #0000ff
shipped7 real palettes, including CVS's brand system and Tesco's brand system put Blue beside #3f5178, as the supporting colour.
Cadet Blue #5f9ea0
shippedDesigners have shipped Cadet Blue with #3f5178: 4 real palettes, including Dusk and Open House, as the supporting colour.
Crimson #dc143c
shippedCrimson is paired with #3f5178 in 13 real palettes, including Codecademy's brand system and Walgreens's brand system, as the accent.
Denim #1560bd
shippedDesigners have shipped Denim with #3f5178: 16 real palettes, including HP's brand system and Hinge's brand system, as the accent.
Firebrick #b22222
shippedDesigners have shipped Firebrick with #3f5178: 4 real palettes, including Fireside and Campbell's's brand system, as the lead colour.
White Smoke #f5f5f5
neutralWhite Smoke is the surface for #3f5178: a clean near-white with no warm cast, so the cool hue stays clear instead of drifting muddy.
Real palettes that use #3f5178
Tints & shades
Harmonies
Contrast
| #3f5178 as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 7.9:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 2.66:1 | 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 #3f5178 as the background.
Brands using this color
No public brand in the corpus uses this exact color yet. Extract a brand to add one.
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 #3f5178 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
/palettes/new/3f5178-9ca4c4-df6b4e-211f2d-e9eff1?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