Color

#313a4e

#313a4e
hex#313a4e
rgbrgb(49, 58, 78)
hslhsl(221, 23%, 25%)
oklchoklch(0.349 0.037 265.7)
Closest name: After Midnight (#38393f)Relative luminance 0.0423

Colors that go with #313a4e

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 →

#4e4531

#31494e · #36314e

#4e313a · #3a4e31

Split-complementary

Open in tool →

#4e3631 · #494e31

#4e3149 · #4e4531 · #314e36

Contrast

#313a4e as textRatioAAAA largeAAAFix
Aaon white
11.38:1passpasspassPasses AAA — no fix needed.
Aaon black
1.85:1failfailfail
  • AA: use #62759d as the text (4.55:1)
  • AAA: use #8896b4 as the text (7.07:1)
  • AA: or shift the background to #a3a3a3 (4.51:1)
  • AAA: or shift the background to #cccccc (7.08:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #313a4e as the background.

Brands using this color

Fonts for this mood

#313a4e reads as cool, muted, dark. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #313a4e
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 #313a4e and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/313a4e-9ca4c4-df6b4e-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