#679FD5

CSS

:root {
  --blue-bay: #679fd5;
  --blue-bay-rgb: 103 159 213;
  --blue-bay-oklch: oklch(0.686 0.1 248.6);
}

.element {
  color: var(--blue-bay);
  background-color: hsl(209 57% 62%);
  border-color: oklch(0.686 0.1 248.6);
}

Tailwind CSS v4

@theme {
  --color-blue-bay: #679fd5;
  --color-blue-bay-50: #e1f8ff;
  --color-blue-bay-100: #d0ebff;
  --color-blue-bay-200: #b5d8fe;
  --color-blue-bay-300: #91bce9;
  --color-blue-bay-400: #6ea3d7;
  --color-blue-bay-500: #4d8bc5;
  --color-blue-bay-600: #4276a6;
  --color-blue-bay-700: #345e86;
  --color-blue-bay-800: #234563;
  --color-blue-bay-900: #173045;
  --color-blue-bay-950: #081c2d;
}

SCSS

$blue-bay: #679fd5;
$blue-bay-rgb: 103, 159, 213;
$blue-bay-light: mix(#fff, $blue-bay, 20%);
$blue-bay-dark: mix(#000, $blue-bay, 20%);

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