Color

#3978d0

#3978d0
hex#3978d0
rgbrgb(57, 120, 208)
hslhsl(215, 62%, 52%)
oklchoklch(0.576 0.15 257.4)
Closest name: Haddock’s Sweater (#277aba)Relative luminance 0.1886

Colors that go with #3978d0

Charcoal, Copper and Amber 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 →

#d09139

#39c4d0 · #4539d0

#d03978 · #78d039

Split-complementary

Open in tool →

#d04539 · #c4d039

#d039c4 · #d09139 · #39d045

Contrast

#3978d0 as textRatioAAAA largeAAAFix
Aaon white
4.4:1failpassfail
  • AA: use #3575d0 as the text (4.56:1)
  • AAA: use #25579d as the text (7.17:1)
  • AA: or shift the background to #080808 (4.55:1)
Aaon black
4.77:1passpassfail
  • AAA: use #6697db as the text (7.01:1)

Fixes keep hue and saturation and move lightness only, so the suggestion stays on-brand. Ratios are symmetric: the same numbers apply with #3978d0 as the background.

Brands using this color

Fonts for this mood

#3978d0 reads as cool, vivid, technical. The font library is tagged with the same vocabulary:

mcpConnect your agent — build around #3978d0
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 #3978d0 and generate a 5-color palette that keeps it as the primary; give me the /palettes/new link

tool url/palettes/new/3978d0-9ca8c4-df5d4e-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