relative visited link color

Using the relative color syntax, you can reuse the link color and define a slightly darker color by subtracting lightness from the original color.

html {
  --color-link: oklch(0.63 0.2 9.96);
}

a:link {
  color: var(--color-link);
}

a:visited {
  color: oklch(from var(--color-link) calc(l - 0.1) c h);
}