#BCE1F3

CSS

:root {
  --sleepless-blue: #bce1f3;
  --sleepless-blue-rgb: 188 225 243;
  --sleepless-blue-oklch: oklch(0.889 0.046 228.9);
}

.element {
  color: var(--sleepless-blue);
  background-color: hsl(200 70% 85%);
  border-color: oklch(0.889 0.046 228.9);
}

Tailwind CSS v4

@theme {
  --color-sleepless-blue: #bce1f3;
  --color-sleepless-blue-50: #e9f8ff;
  --color-sleepless-blue-100: #d9ebf5;
  --color-sleepless-blue-200: #c1d8e5;
  --color-sleepless-blue-300: #a0bccb;
  --color-sleepless-blue-400: #83a4b4;
  --color-sleepless-blue-500: #668d9f;
  --color-sleepless-blue-600: #577786;
  --color-sleepless-blue-700: #455f6b;
  --color-sleepless-blue-800: #31464f;
  --color-sleepless-blue-900: #213037;
  --color-sleepless-blue-950: #111d22;
}

SCSS

$sleepless-blue: #bce1f3;
$sleepless-blue-rgb: 188, 225, 243;
$sleepless-blue-light: mix(#fff, $sleepless-blue, 20%);
$sleepless-blue-dark: mix(#000, $sleepless-blue, 20%);

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