River Blue

CSS

:root {
  --river-blue: #38afcd;
  --river-blue-rgb: 56 175 205;
  --river-blue-oklch: oklch(0.702 0.111 218.5);
}

.element {
  color: var(--river-blue);
  background-color: hsl(192 60% 51%);
  border-color: oklch(0.702 0.111 218.5);
}

Tailwind CSS v4

@theme {
  --color-river-blue: #38afcd;
  --color-river-blue-50: #d3fdff;
  --color-river-blue-100: #c0f1ff;
  --color-river-blue-200: #9fe0f5;
  --color-river-blue-300: #72c5df;
  --color-river-blue-400: #41aeca;
  --color-river-blue-500: #0097b7;
  --color-river-blue-600: #007f9b;
  --color-river-blue-700: #00667c;
  --color-river-blue-800: #004b5b;
  --color-river-blue-900: #003440;
  --color-river-blue-950: #002029;
}

SCSS

$river-blue: #38afcd;
$river-blue-rgb: 56, 175, 205;
$river-blue-light: mix(#fff, $river-blue, 20%);
$river-blue-dark: mix(#000, $river-blue, 20%);

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