Color

#04378f

#04378f
hex#04378f
rgbrgb(4, 55, 143)
hslhsl(218, 95%, 29%)
oklchoklch(0.37 0.154 261.1)
Closest name: Deep Space Royal (#223382)Relative luminance 0.0474

Colors that go with #04378f

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.

Tints & shades

Every swatch is its own page — click any to analyze it.

Harmonies

Complementary

Open in tool →

#905d04

#047d90 · #160490

#900437 · #379004

Split-complementary

Open in tool →

#901604 · #7d9004

#90047d · #905d04 · #049016

Contrast

#04378f as textRatioAAAA largeAAAFix
Aaon white
10.78:1passpasspassPasses AAA — no fix needed.
Aaon black
1.95:1failfailfail
  • AA: use #1a6cf9 as the text (4.56:1)
  • AAA: use #5b96fb as the text (7.2:1)
  • AA: or shift the background to #a8a8a8 (4.53:1)
  • AAA: or shift the background to #d1d1d1 (7.06:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #04378f as the background.

Brands using this color

Palettes built around it

Fonts for this mood

#04378f reads as cool, vivid, dark. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #04378f
live endpoint

Point 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.

endpointhttps://mcp.brandsweets.com/colors/mcp
claude mcp add --transport http brandsweets-colors https://mcp.brandsweets.com/colors/mcp
try this prompt

analyze #04378f and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/04378f-9ca6c4-df644e-201f2d-e9f0f1?lock=0&style=vibrant

Want the agent to remember your picks and write them into a living brand? Create a free BrandSweets workspace.

Machine-readable: color.md