#B55B35

CSS

:root {
  --monument-valley: #b55b35;
  --monument-valley-rgb: 181 91 53;
  --monument-valley-oklch: oklch(0.573 0.128 42.5);
}

.element {
  color: var(--monument-valley);
  background-color: hsl(18 55% 46%);
  border-color: oklch(0.573 0.128 42.5);
}

Tailwind CSS v4

@theme {
  --color-monument-valley: #b55b35;
  --color-monument-valley-50: #ffead8;
  --color-monument-valley-100: #ffdbc5;
  --color-monument-valley-200: #ffc3a8;
  --color-monument-valley-300: #efa281;
  --color-monument-valley-400: #dd845f;
  --color-monument-valley-500: #ca653a;
  --color-monument-valley-600: #ab5633;
  --color-monument-valley-700: #894528;
  --color-monument-valley-800: #66311d;
  --color-monument-valley-900: #482113;
  --color-monument-valley-950: #2f1005;
}

SCSS

$monument-valley: #b55b35;
$monument-valley-rgb: 181, 91, 53;
$monument-valley-light: mix(#fff, $monument-valley, 20%);
$monument-valley-dark: mix(#000, $monument-valley, 20%);

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