Nakshora 1.0 predates the modifier syntax. For translucency, either pick a pre-blended shade or override the variable:

css
.my-overlay {
  background: hsl(280 100% 55% / 0.5); /* neon-purple-500 at 50% */
}

The modern releases (v3.1 opacity modifiers) support /0–/100 on every color utility.