#42A3DF

CSS

:root {
  --high-blue: #42a3df;
  --high-blue-rgb: 66 163 223;
  --high-blue-oklch: oklch(0.684 0.126 239.7);
}

.element {
  color: var(--high-blue);
  background-color: hsl(203 71% 57%);
  border-color: oklch(0.684 0.126 239.7);
}

Tailwind CSS v4

@theme {
  --color-high-blue: #42a3df;
  --color-high-blue-50: #d6fbff;
  --color-high-blue-100: #c4eeff;
  --color-high-blue-200: #a4dcff;
  --color-high-blue-300: #7bc0f2;
  --color-high-blue-400: #4ea8e1;
  --color-high-blue-500: #0c8fd0;
  --color-high-blue-600: #1379b0;
  --color-high-blue-700: #10618d;
  --color-high-blue-800: #044868;
  --color-high-blue-900: #043249;
  --color-high-blue-950: #001d30;
}

SCSS

$high-blue: #42a3df;
$high-blue-rgb: 66, 163, 223;
$high-blue-light: mix(#fff, $high-blue, 20%);
$high-blue-dark: mix(#000, $high-blue, 20%);

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