Hexadecimal colors

Hex color notation encodes sRGB channels in base 16. In #317CFF, 31 is red, 7C is green, and FF is blue. Each channel ranges from 00 to FF. An optional fourth pair encodes alpha, from transparent 00 to opaque FF.

Hex is a convenient handoff format for brand swatches. It does not expose a perceived-lightness value, so use the color engine or CSS relative colors when you need related shades.

Use hex as a theme seed

A theme's seedColor accepts #rrggbb, as well as rgb(), hsl(), and oklch(). Espalier converts supported inputs to OKLCH before generating the palette. For example, seedColor: '#78486A' and its converted oklch(0.469 0.0809 338.5) represent the same source color.

See theming for configuration and brand fitting for preserving supplied swatches.

Derive a color in CSS

.button {
  --seed-hex: #317CFF;
  background: oklch(from var(--seed-hex) l c h);
}

.button:hover {
  background: oklch(from var(--seed-hex) calc(l + 0.05) c h);
}

For component styling, prefer semantic tokens that follow the active theme. Derived custom colors need their own contrast checks.