#899EA3

CSS

:root {
  --inland-waters: #899ea3;
  --inland-waters-rgb: 137 158 163;
  --inland-waters-oklch: oklch(0.685 0.025 213.7);
}

.element {
  color: var(--inland-waters);
  background-color: hsl(192 12% 59%);
  border-color: oklch(0.685 0.025 213.7);
}

Tailwind CSS v4

@theme {
  --color-inland-waters: #899ea3;
  --color-inland-waters-50: #eef7fa;
  --color-inland-waters-100: #dfeaed;
  --color-inland-waters-200: #c9d7db;
  --color-inland-waters-300: #aabbbf;
  --color-inland-waters-400: #8fa3a7;
  --color-inland-waters-500: #748b90;
  --color-inland-waters-600: #62757a;
  --color-inland-waters-700: #4f5e62;
  --color-inland-waters-800: #394547;
  --color-inland-waters-900: #273031;
  --color-inland-waters-950: #151c1d;
}

SCSS

$inland-waters: #899ea3;
$inland-waters-rgb: 137, 158, 163;
$inland-waters-light: mix(#fff, $inland-waters, 20%);
$inland-waters-dark: mix(#000, $inland-waters, 20%);

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