#636D7A

CSS

:root {
  --ashen-whisper: #636d7a;
  --ashen-whisper-rgb: 99 109 122;
  --ashen-whisper-oklch: oklch(0.531 0.024 255);
}

.element {
  color: var(--ashen-whisper);
  background-color: hsl(214 10% 43%);
  border-color: oklch(0.531 0.024 255);
}

Tailwind CSS v4

@theme {
  --color-ashen-whisper: #636d7a;
  --color-ashen-whisper-50: #f1f5fc;
  --color-ashen-whisper-100: #e3e8f0;
  --color-ashen-whisper-200: #ced5df;
  --color-ashen-whisper-300: #b0b8c4;
  --color-ashen-whisper-400: #959fad;
  --color-ashen-whisper-500: #7c8796;
  --color-ashen-whisper-600: #69727f;
  --color-ashen-whisper-700: #545c66;
  --color-ashen-whisper-800: #3d434b;
  --color-ashen-whisper-900: #2a2e34;
  --color-ashen-whisper-950: #171b1f;
}

SCSS

$ashen-whisper: #636d7a;
$ashen-whisper-rgb: 99, 109, 122;
$ashen-whisper-light: mix(#fff, $ashen-whisper, 20%);
$ashen-whisper-dark: mix(#000, $ashen-whisper, 20%);

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