#A43E08

CSS

:root {
  --rust: #a43e08;
  --rust-rgb: 164 62 8;
  --rust-oklch: oklch(0.499 0.146 42);
}

.element {
  color: var(--rust);
  background-color: hsl(21 91% 34%);
  border-color: oklch(0.499 0.146 42);
}

Tailwind CSS v4

@theme {
  --color-rust: #a43e08;
  --color-rust-50: #ffe9d4;
  --color-rust-100: #ffd9c1;
  --color-rust-200: #ffc1a1;
  --color-rust-300: #f69e78;
  --color-rust-400: #e57e55;
  --color-rust-500: #d35e2b;
  --color-rust-600: #b25026;
  --color-rust-700: #8f401e;
  --color-rust-800: #6b2d16;
  --color-rust-900: #4b1f0e;
  --color-rust-950: #310e02;
}

SCSS

$rust: #a43e08;
$rust-rgb: 164, 62, 8;
$rust-light: mix(#fff, $rust, 20%);
$rust-dark: mix(#000, $rust, 20%);

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