#315E8C

CSS

:root {
  --mississippi-river: #315e8c;
  --mississippi-river-rgb: 49 94 140;
  --mississippi-river-oklch: oklch(0.472 0.09 250.7);
}

.element {
  color: var(--mississippi-river);
  background-color: hsl(210 48% 37%);
  border-color: oklch(0.472 0.09 250.7);
}

Tailwind CSS v4

@theme {
  --color-mississippi-river: #315e8c;
  --color-mississippi-river-50: #e3f7ff;
  --color-mississippi-river-100: #d3eaff;
  --color-mississippi-river-200: #bad7fb;
  --color-mississippi-river-300: #97bbe5;
  --color-mississippi-river-400: #76a2d2;
  --color-mississippi-river-500: #578ac0;
  --color-mississippi-river-600: #4a75a2;
  --color-mississippi-river-700: #3b5d82;
  --color-mississippi-river-800: #284560;
  --color-mississippi-river-900: #1b3043;
  --color-mississippi-river-950: #0b1c2c;
}

SCSS

$mississippi-river: #315e8c;
$mississippi-river-rgb: 49, 94, 140;
$mississippi-river-light: mix(#fff, $mississippi-river, 20%);
$mississippi-river-dark: mix(#000, $mississippi-river, 20%);

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