#646D7B

CSS

:root {
  --ashen-whisper: #646d7b;
  --ashen-whisper-rgb: 100 109 123;
  --ashen-whisper-oklch: oklch(0.532 0.025 259.2);
}

.element {
  color: var(--ashen-whisper);
  background-color: hsl(217 10% 44%);
  border-color: oklch(0.532 0.025 259.2);
}

Tailwind CSS v4

@theme {
  --color-ashen-whisper: #646d7b;
  --color-ashen-whisper-50: #f1f5fc;
  --color-ashen-whisper-100: #e3e8f0;
  --color-ashen-whisper-200: #ced5df;
  --color-ashen-whisper-300: #b0b8c4;
  --color-ashen-whisper-400: #969fad;
  --color-ashen-whisper-500: #7d8797;
  --color-ashen-whisper-600: #6a7280;
  --color-ashen-whisper-700: #545b66;
  --color-ashen-whisper-800: #3d434b;
  --color-ashen-whisper-900: #2a2e34;
  --color-ashen-whisper-950: #181b20;
}

SCSS

$ashen-whisper: #646d7b;
$ashen-whisper-rgb: 100, 109, 123;
$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);
}