Blueprint
Open in tool →Cyan and indigo on navy is the developer-tool look; amber is the only warm note, so it always reads as 'attention'.
Color
#031a2b
#031a2b
hex
#031a2brgb
rgb(3, 26, 43)hsl
hsl(206, 87%, 9%)oklch
oklch(0.209 0.045 243.2)Closest name: Dark Knight (#151931)Relative luminance 0.0093
Colors that go with #031a2b
Charcoal, Royal Blue and Rust 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 #031a2b: softer than #000 and cool enough to feel like part of the same palette.
Royal Blue #4169e1
analogousshippedRoyal Blue is #031a2b's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces.
Rust #b7410e
split-complementshippedRust is a split-complement of #031a2b: nearly opposite, so it still pops against it, without the vibrating edge of a true complement.
Sienna #a0522d
complementaryshippedSienna sits directly opposite #031a2b on the wheel — the strongest contrast one hue can give another, so use it small: a button, a link colour, one highlight.
Teal #008080
analogousshippedTeal is #031a2b'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 #031a2b in 15 real palettes, including Blueprint and Lemon Squeezy's brand system, as the accent — a combination designers have actually shipped, not a computed rotation.
Blue #0000ff
shippedBlue is paired with #031a2b in 23 real palettes, including Monzo's brand system and League of Legends's brand system, as the accent — a combination designers have actually shipped, not a computed rotation.
Blue Violet #8a2be2
shippedBlue Violet is paired with #031a2b in 10 real palettes, including Yahoo's brand system and Prepare your taste buds...'s brand system, as the supporting colour — a combination designers have actually shipped, not a computed rotation.
Real palettes that use #031a2b
Tints & shades
Harmonies
Contrast
| #031a2b as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 17.7:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 1.19:1 | 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 #031a2b as the background.
Brands using this color
Palettes built around it
Indigo SaaS
Open in tool →The dependable indigo-and-emerald B2B pairing: indigo for primary actions, emerald reserved for success states.
Slate Workspace
Open in tool →Slate on slate with a single blue — the productivity-app look where the interface disappears behind the work.
Clinic
Open in tool →Teal reads clinical without the coldness of pure blue; the coral accent adds warmth for reassurance moments.
Arctic
Open in tool →Navy type on white with an ice-blue accent: crisp and corporate without going grey.
Cobalt Pop
Open in tool →One deep cobalt and one hot pink on white — a two-accent system for launches and campaign pages that need punch.
Sapphire & Gold
Open in tool →Deep sapphire and gold with a teal — old-money jewel tones on an ivory ground; heraldic without a crest.
Peacock
Open in tool →Teal, cobalt and magenta at full chroma on white — jewel tones in daylight; the trick is a near-black text with a blue cast.
Fonts for this mood
#031a2b reads as cool, vivid, dark. The font library is tagged with the same vocabulary:
mcpConnect your agent — build around #031a2b
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 #031a2b and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/031a2b-9caec4-df4e56-1f212d-e9f1f1?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