Color
#370d91
#370d91rgb(55, 13, 145)hsl(259, 84%, 31%)oklch(0.339 0.187 284.8)Colors that go with #370d91
Royal Blue, Cobalt Blue and Crimson 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 #370d91's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces.
Cobalt Blue #0047ab
shippedDesigners have shipped Cobalt Blue with #370d91: 4 real palettes, including Tide's brand system and Purina Pro Plan's brand system, as the lead colour.
Crimson #dc143c
shippedCrimson is paired with #370d91 in 4 real palettes, including Pepsi's brand system and Casper Sleep's brand system, as the supporting colour.
Denim #1560bd
shippedDesigners have shipped Denim with #370d91: 4 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 #370d91: 4 real palettes, including FedEx's brand system and Hershey's's brand system, as the accent.
Olive Green #808000
complementaryOlive Green sits directly opposite #370d91 on the wheel — the strongest contrast one hue can give another, so use it small: a button, a link colour, one highlight.
Blue #0000ff
shipped3 real palettes, including Procter & Gamble's brand system and Zillow's brand system put Blue beside #370d91, as the supporting colour.
Charcoal #36454f
neutralshippedCharcoal is the text near-black for #370d91: softer than #000 and cool enough to feel like part of the same palette.
Real palettes that use #370d91
Tints & shades
Harmonies
Contrast
| #370d91 as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 12.89:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 1.63:1 | 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 #370d91 as the background.
Brands using this color
Fonts for this mood
#370d91 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 #370d91 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
/palettes/new/370d91-ad9cc4-dfc74e-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