#679FD8

CSS

:root {
  --blue-bay: #679fd8;
  --blue-bay-rgb: 103 159 216;
  --blue-bay-oklch: oklch(0.687 0.103 249.9);
}

.element {
  color: var(--blue-bay);
  background-color: hsl(210 59% 63%);
  border-color: oklch(0.687 0.103 249.9);
}

Tailwind CSS v4

@theme {
  --color-blue-bay: #679fd8;
  --color-blue-bay-50: #e0f8ff;
  --color-blue-bay-100: #d0ebff;
  --color-blue-bay-200: #b5d8ff;
  --color-blue-bay-300: #91bbeb;
  --color-blue-bay-400: #6ea3d9;
  --color-blue-bay-500: #4c8ac8;
  --color-blue-bay-600: #4175a9;
  --color-blue-bay-700: #345e87;
  --color-blue-bay-800: #234564;
  --color-blue-bay-900: #173046;
  --color-blue-bay-950: #081c2e;
}

SCSS

$blue-bay: #679fd8;
$blue-bay-rgb: 103, 159, 216;
$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);
}