#DE0800

CSS

:root {
  --red-pegasus: #de0800;
  --red-pegasus-rgb: 222 8 0;
  --red-pegasus-oklch: oklch(0.567 0.23 29.6);
}

.element {
  color: var(--red-pegasus);
  background-color: hsl(2 100% 44%);
  border-color: oklch(0.567 0.23 29.6);
}

Tailwind CSS v4

@theme {
  --color-red-pegasus: #de0800;
  --color-red-pegasus-50: #ffddcc;
  --color-red-pegasus-100: #ffcbb8;
  --color-red-pegasus-200: #ffad96;
  --color-red-pegasus-300: #ff8369;
  --color-red-pegasus-400: #ff5744;
  --color-red-pegasus-500: #fa0500;
  --color-red-pegasus-600: #d31207;
  --color-red-pegasus-700: #aa1108;
  --color-red-pegasus-800: #80070b;
  --color-red-pegasus-900: #5a0607;
  --color-red-pegasus-950: #3d0000;
}

SCSS

$red-pegasus: #de0800;
$red-pegasus-rgb: 222, 8, 0;
$red-pegasus-light: mix(#fff, $red-pegasus, 20%);
$red-pegasus-dark: mix(#000, $red-pegasus, 20%);

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