Color

#313b54

#313b54
hex#313b54
rgbrgb(49, 59, 84)
hslhsl(223, 26%, 26%)
oklchoklch(0.355 0.046 267.3)
Closest name: Capital Blue (#1a4157)Relative luminance 0.0442

Colors that go with #313b54

Dark Olive Green, Sea Green 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 →

#544a31

#314c54 · #393154

#54313b · #3b5431

Split-complementary

Open in tool →

#543931 · #4c5431

#54314c · #544a31 · #315439

Contrast

#313b54 as textRatioAAAA largeAAAFix
Aaon white
11.15:1passpasspassPasses AAA — no fix needed.
Aaon black
1.88:1failfailfail
  • AA: use #6274a3 as the text (4.55:1)
  • AAA: use #8896b9 as the text (7.11:1)
  • AA: or shift the background to #a6a6a6 (4.58:1)
  • AAA: or shift the background to #cfcfcf (7.15:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #313b54 as the background.

Brands using this color

Fonts for this mood

#313b54 reads as cool, muted, dark. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #313b54
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 #313b54 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/313b54-9ca3c4-df704e-211f2d-e9eff1?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