Ink & Paper
Open in tool →Two greys and one ink-blue link color: the palette of a well-set book page.
Color
#0b3fa8
#0b3fa8
hex
#0b3fa8rgb
rgb(11, 63, 168)hsl
hsl(220, 88%, 35%)oklch
oklch(0.411 0.177 262.3)Closest name: Cobalt Blue (#0047ab)Relative luminance 0.0645
Colors that go with #0b3fa8
Charcoal, Crimson and Steel Blue 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 #0b3fa8: softer than #000 and cool enough to feel like part of the same palette.
Crimson #dc143c
triadicshippedCrimson completes a triad with #0b3fa8 — three hues spaced evenly round the wheel, the classic way to get energy into a palette without a clash.
Steel Blue #4682b4
analogousshippedSteel Blue is #0b3fa8's neighbour on the wheel, so the two read as one family — use it for hover states, gradients and secondary surfaces.
Blue #0000ff
shipped7 real palettes, including Procter & Gamble's brand system and CVS's brand system put Blue beside #0b3fa8, as the supporting colour.
Cornflower Blue #6495ed
shippedDesigners have shipped Cornflower Blue with #0b3fa8: 5 real palettes, including Blue Mono and Gopro's brand system, as the supporting colour.
Firebrick #b22222
shippedDesigners have shipped Firebrick with #0b3fa8: 6 real palettes, including MLB's brand system and 3M's brand system, as the supporting colour.
Midnight Blue #191970
shipped17 real palettes, including Blue Mono and Air France's brand system put Midnight Blue beside #0b3fa8, as that palette's text colour.
Orange Red #ff4500
shippedOrange Red is paired with #0b3fa8 in 5 real palettes, including NASA's brand system and Tide's brand system, as the supporting colour.
Real palettes that use #0b3fa8
Tints & shades
Harmonies
Contrast
| #0b3fa8 as text | Ratio | AA | AA large | AAA | Fix |
|---|---|---|---|---|---|
Aaon white | 9.17:1 | pass | pass | pass | Passes AAA — no fix needed. |
Aaon black | 2.29:1 | 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 #0b3fa8 as the background.
Brands using this color
Palettes built around it
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.
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.
Fonts for this mood
#0b3fa8 reads as cool, vivid, technical. The font library is tagged with the same vocabulary:
mcpConnect your agent — build around #0b3fa8
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 #0b3fa8 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link
tool url
/palettes/new/0b3fa8-9ca5c4-df694e-211f2d-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