Blue Mono
Open in tool →One blue at four lightnesses — monochromatic in the colour-theory sense; the deep step is the text, the pale step the surface tint.
Color
#181f59
#181f59
hex
#181f59rgb
rgb(24, 31, 89)hsl
hsl(234, 58%, 22%)oklch
oklch(0.274 0.104 272.3)Closest name: Dark Soul (#112255)Relative luminance 0.019
Colors that go with #181f59
Charcoal, Dark Olive Green and Sea Green 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 #181f59: softer than #000 and cool enough to feel like part of the same palette.
Dark Olive Green #556b2f
split-complementshippedDark Olive Green is a split-complement of #181f59: nearly opposite, so it still pops against it, without the vibrating edge of a true complement.
Sea Green #2e8b57
triadicshippedSea Green completes a triad with #181f59 — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash.
Slate Blue #6a5acd
analogousshippedSlate Blue is #181f59's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces.
Steel Blue #4682b4
analogousshippedSteel Blue is #181f59's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces.
Amber #ffbf00
shippedAmber is paired with #181f59 in 7 real palettes, including Southwest Airlines's brand system and Beach Hut, as the accent.
Blue #0000ff
shipped15 real palettes, including Monzo's brand system and Sketch's brand system put Blue beside #181f59, as the accent.
Burlywood #deb887
shippedBurlywood is paired with #181f59 in 4 real palettes, including Coastal and Chalkboard, as the accent.
Real palettes that use #181f59
Tints & shades
Harmonies
Contrast
| #181f59 as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 15.23:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 1.38:1 | 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 #181f59 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
#181f59 reads as cool, dark, luxury. The font library is tagged with the same vocabulary:
mcpConnect your agent — build around #181f59
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 #181f59 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/181f59-9d9cc4-df8a4e-241f2d-e9eef1?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