#E51445

CSS

:root {
  --crossing-the-line: #e51445;
  --crossing-the-line-rgb: 229 20 69;
  --crossing-the-line-oklch: oklch(0.589 0.229 18.2);
}

.element {
  color: var(--crossing-the-line);
  background-color: hsl(346 84% 49%);
  border-color: oklch(0.589 0.229 18.2);
}

Tailwind CSS v4

@theme {
  --color-crossing-the-line: #e51445;
  --color-crossing-the-line-50: #ffdbda;
  --color-crossing-the-line-100: #ffc9c8;
  --color-crossing-the-line-200: #ffaaab;
  --color-crossing-the-line-300: #ff8085;
  --color-crossing-the-line-400: #ff5368;
  --color-crossing-the-line-500: #f90047;
  --color-crossing-the-line-600: #d2083d;
  --color-crossing-the-line-700: #a90b30;
  --color-crossing-the-line-800: #7f0425;
  --color-crossing-the-line-900: #5a0519;
  --color-crossing-the-line-950: #3c000a;
}

SCSS

$crossing-the-line: #e51445;
$crossing-the-line-rgb: 229, 20, 69;
$crossing-the-line-light: mix(#fff, $crossing-the-line, 20%);
$crossing-the-line-dark: mix(#000, $crossing-the-line, 20%);

.element {
  color: $crossing-the-line;
  box-shadow: 0 0 0 2px rgba($crossing-the-line, 0.35);
}