Ultramarine Blue

CSS

:root {
  --ultramarine-blue: #657abb;
  --ultramarine-blue-rgb: 101 122 187;
  --ultramarine-blue-oklch: oklch(0.591 0.103 269.5);
}

.element {
  color: var(--ultramarine-blue);
  background-color: hsl(225 39% 56%);
  border-color: oklch(0.591 0.103 269.5);
}

Tailwind CSS v4

@theme {
  --color-ultramarine-blue: #657abb;
  --color-ultramarine-blue-50: #eaf4ff;
  --color-ultramarine-blue-100: #dbe7ff;
  --color-ultramarine-blue-200: #c4d3ff;
  --color-ultramarine-blue-300: #a4b5ed;
  --color-ultramarine-blue-400: #869cdc;
  --color-ultramarine-blue-500: #6b82ca;
  --color-ultramarine-blue-600: #5b6eab;
  --color-ultramarine-blue-700: #485889;
  --color-ultramarine-blue-800: #334166;
  --color-ultramarine-blue-900: #222d48;
  --color-ultramarine-blue-950: #12192f;
}

SCSS

$ultramarine-blue: #657abb;
$ultramarine-blue-rgb: 101, 122, 187;
$ultramarine-blue-light: mix(#fff, $ultramarine-blue, 20%);
$ultramarine-blue-dark: mix(#000, $ultramarine-blue, 20%);

.element {
  color: $ultramarine-blue;
  box-shadow: 0 0 0 2px rgba($ultramarine-blue, 0.35);
}