#51A2DB

CSS

:root {
  --high-blue: #51a2db;
  --high-blue-rgb: 81 162 219;
  --high-blue-oklch: oklch(0.685 0.116 241.8);
}

.element {
  color: var(--high-blue);
  background-color: hsl(205 66% 59%);
  border-color: oklch(0.685 0.116 241.8);
}

Tailwind CSS v4

@theme {
  --color-high-blue: #51a2db;
  --color-high-blue-50: #dafaff;
  --color-high-blue-100: #c8edff;
  --color-high-blue-200: #aadbff;
  --color-high-blue-300: #83beef;
  --color-high-blue-400: #5ba6dd;
  --color-high-blue-500: #2e8ecc;
  --color-high-blue-600: #2978ac;
  --color-high-blue-700: #21608a;
  --color-high-blue-800: #134766;
  --color-high-blue-900: #0c3148;
  --color-high-blue-950: #011d2f;
}

SCSS

$high-blue: #51a2db;
$high-blue-rgb: 81, 162, 219;
$high-blue-light: mix(#fff, $high-blue, 20%);
$high-blue-dark: mix(#000, $high-blue, 20%);

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