#2D3F50

CSS

:root {
  --one-year-of-rain: #2d3f50;
  --one-year-of-rain-rgb: 45 63 80;
  --one-year-of-rain-oklch: oklch(0.36 0.038 247.5);
}

.element {
  color: var(--one-year-of-rain);
  background-color: hsl(209 28% 25%);
  border-color: oklch(0.36 0.038 247.5);
}

Tailwind CSS v4

@theme {
  --color-one-year-of-rain: #2d3f50;
  --color-one-year-of-rain-50: #edf6ff;
  --color-one-year-of-rain-100: #dfe9f4;
  --color-one-year-of-rain-200: #c8d6e4;
  --color-one-year-of-rain-300: #a9b9ca;
  --color-one-year-of-rain-400: #8da1b4;
  --color-one-year-of-rain-500: #73899e;
  --color-one-year-of-rain-600: #617486;
  --color-one-year-of-rain-700: #4e5d6b;
  --color-one-year-of-rain-800: #38444f;
  --color-one-year-of-rain-900: #262f37;
  --color-one-year-of-rain-950: #141b22;
}

SCSS

$one-year-of-rain: #2d3f50;
$one-year-of-rain-rgb: 45, 63, 80;
$one-year-of-rain-light: mix(#fff, $one-year-of-rain, 20%);
$one-year-of-rain-dark: mix(#000, $one-year-of-rain, 20%);

.element {
  color: $one-year-of-rain;
  box-shadow: 0 0 0 2px rgba($one-year-of-rain, 0.35);
}