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
#10274c
#10274c
hex
#10274crgb
rgb(16, 39, 76)hsl
hsl(217, 65%, 18%)oklch
oklch(0.277 0.074 259.5)Closest name: Midnight Ocean (#0f2d4d)Relative luminance 0.0208
Colors that go with #10274c
Charcoal, Rust 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 #10274c: softer than #000 and cool enough to feel like part of the same palette.
Rust #b7410e
triadicshippedRust completes a triad with #10274c — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash.
Sea Green #2e8b57
triadicshippedSea Green completes a triad with #10274c — 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 #10274c on the wheel — the strongest contrast one hue can give another, so use it small: a button, a link colour, one highlight.
Slate Blue #6a5acd
analogousshippedSlate Blue is #10274c'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 #10274c'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 #10274c in 10 real palettes, including Southwest Airlines's brand system and Beach Hut, as the accent.
Blue #0000ff
shipped19 real palettes, including Monzo's brand system and Sketch's brand system put Blue beside #10274c, as the accent.
Real palettes that use #10274c
Tints & shades
Harmonies
Contrast
| #10274c as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 14.82:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 1.42:1 | 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 #10274c as the background.
Brands using this color
Palettes built around it
Fonts for this mood
#10274c reads as cool, vivid, dark. The font library is tagged with the same vocabulary:
mcpConnect your agent — build around #10274c
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 #10274c and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/10274c-9ca7c4-df624e-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