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
#212554
#212554
hex
#212554rgb
rgb(33, 37, 84)hsl
hsl(235, 44%, 23%)oklch
oklch(0.289 0.084 276.1)Closest name: Dark Soul (#112255)Relative luminance 0.0229
Colors that go with #212554
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 #212554: softer than #000 and cool enough to feel like part of the same palette.
Dark Olive Green #556b2f
complementaryshippedDark Olive Green sits directly opposite #212554 on the wheel — the strongest contrast one hue can give another, so use it small: a button, a link colour, one highlight.
Sea Green #2e8b57
triadicshippedSea Green completes a triad with #212554 — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash.
Sienna #a0522d
split-complementshippedSienna is a split-complement of #212554: nearly opposite, so it still pops against it, without the vibrating edge of a true complement.
Slate Blue #6a5acd
analogousshippedSlate Blue is #212554'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 #212554'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 #212554 in 7 real palettes, including Southwest Airlines's brand system and Beach Hut, as the accent.
Blue #0000ff
shipped17 real palettes, including Sketch's brand system and Monzo's brand system put Blue beside #212554, as the accent.
Real palettes that use #212554
Tints & shades
Harmonies
Contrast
| #212554 as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 14.41:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 1.46:1 | 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 #212554 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
#212554 reads as cool, dark, luxury. The font library is tagged with the same vocabulary:
mcpConnect your agent — build around #212554
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 #212554 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/212554-9e9cc4-df8d4e-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